The following includes references that I believe will help answer your questions:

May 20, 21, 23, 24, & 25, 1864-Report of inspection of the Bns of Hvy Arty of the Richmond Defenses:
1st Div, Lt Col J W Atkinson cdg, composed of 10th Va Bn, Maj J 0 Hensley cdg; 19th Va Bn, Maj N R Cary cdg
2nd Div, Lt Col James Howard cdg; composed of 18th Va Bn, Maj M B Hardin cdg; 20th Va Bn, Maj J E Robertson cdg
Disposed on the intermediate line as follows:
Osborne road: One Lt & 11 men—two 24-pdr siege guns with only 20 rounds of ammunition apiece Fort Davis (a work on the extreme left of the line, connecting Chaffin's Bluff with the intermediate line): One Co—one 6-pdr, 60 rounds; one 12-pdr howitzer, 55 rounds
New Market road: Dtchmt Co C, 10th Va Bn—two 6-pdrs, 45 rounds each; two buckets & one trail hand spike needed
Darbytown road: One Co 10th Va Bn—two 32-pdrs, 20 rounds each; three 6-pdrs, 64 rounds each; one 8-inch howitzer
Williamsburg road: Co D, 19th Va Bn; Co’s B & C, 10th Va Bn—two 24-pdr Coehorn mortars, five 12-pdr field guns, one 18-pdr rifle, one 6-pdr, one 8-inch shell gun; 50 rounds for each, except 18-pdr rifle, which has only 39
New Bridge road: Co’s A & C, 19th Va Bn—three 6-pdrs, 150 rounds each; two 24-pdr siege guns, 52 rounds each
Mechanicsville road: Co’s D & E, 10th Va Bn—one 32-pdr siege gun, 62 rounds; two 24-pdr howitzers, 45 rounds each; one 6-pdr, 150 rounds
Meadow Bridge road: Co E, 19th Va Bn—one James 12-pdr rifle, 124 rounds; one 10-pdr Parrott, 98 rounds; one 8 inch howitzer, 40 rounds; one 24-pdr howitzer, 88 rounds; one 32-pdr siege gun, 52 rounds; one 24-pdr siege gun, 50 rounds
Mitchell tract road: Dtchmt Dabney's Co, 20th Va Bn—one 24-pdr howitzer, 42 rounds Main body of 18th Va Bn as Infy
Brook road: Main body 20th Va Bn—one 24-pdr howitzer, 70 rounds; two 32-pdr siege guns, 60 rounds each; one 8-inch howitzer, 40 rounds
Mill road: One officer & 22 men of 20th Bn—two 6-pdrs, 50 rounds each
Deep Run road: One officer & 30 m4n from 20th Bn—two 24-pdr siege guns, 50 rounds each; one 12-pdr howitzer, 49 rounds; one 24-pdr howitzer, 65 rounds; one 6-pdr, 62 rounds Tarpaulin for protection of ammunition bad
Plank road: Co C, 20th Bn—one 6-pdr, 56 rounds; three 24-pdr siege guns, 52 rounds each One ladle for 24-pdr & two lanterns needed
In the work overlooking the canal are two field guns manned by a dtchmt from the Navy Bn
On the south side of James River the intermediate line is incomplete from Broad Rock road to the river on the right The troops
in this quarter are, therefore, posted in the forts of the interior line as follows:
Btry 14: Dtchmt Green's Co La Light Arty (just exchanged)-1 officer & 20 men, one 8-inch shell gun, 40 rounds; one 32-pdr, 40 rounds; three 6-pdrs, 50 rounds each This work is entirely commanded by the ground a few hundred yards in front
Btry 15: Dtchmt of Co D, 18th Va Bn, & Green's La Co—five 32-pdrs, 30 rounds each; two 6-pdrs, 50 rounds each; one 12-pdr howitzer, 26 rounds
Btry 17: Dtchmt (1 officer & 17 men) Green's (La) Co—one 8-inch shell gun, 40 rounds; one 32-pdr, 40 rounds
The following guns are disposed on the intermediate line, each with a dtchmt of 5 men from the 18th Va Bn & Green's (La) Co:
Broad Rock road': One 12-pdr, 40 rounds; two 6-pdrs, 50 rounds each; one 12-pdr howitzer, 40 rounds
Between Broad Rock road & Petersburg RR: One 6-pdr, 50 rounds; one 12-pdr howitzer, 39 rounds
Petersburg RR: One 8-inch shell gun, 100 rounds; one 10-pdr Parrott, 45 rounds
Petersburg turnpike: One 6-pdr, 50 rounds; one 12-pdr howitzer, 39 rounds
2nd Btry from the river: One 6-pdr, 50 rounds
Bn Cdrs report that they have no officers whom it would be expedient to drop for incompetence or drunkenness
There are no schools of tactics
Drill: As Infy, imperfect; in Co’s A & C, 19th Va Bn, bad; as Hvy Arty, good, except dtchmt Co A, 20th Bn, on Mill road, Most of the cdg officers report that owing to the heavy details for guard duty in Richmond during the last ten months they have been unable to drill their commands The morale of these 'troops has been doubtless much impaired by this service Three drills a day have recently been ordered by Gen Pemberton, & the details for city duty are suspended With the exception of two or three
Co’s, which have seen service, the men have had no Arty practice The NCO’s are reported as generally ignorant of the theory of firing
No officers absent without leave; 9 men who received furloughs remain absent without leave Clothing very good; 11 men entirely without shoes, the remainder generally with excellent shoes; 72 men without a blanket These Bns have no transportation
Arms: 1125 smooth-bore, caliber 69; 28 rifled, caliber, 69; 215 rifled, caliber 58; 260 rifled, caliber, 54. In no case were the arms in as good order as is required of troops in garrison; many were rusty, Ammunition for Arty & small-arms in good condition The magazines on the intermediate line are generally damp
Staff Dept’s: Lt-Col Howard has no staff, Lt-Col Atkinson has an Adjt. Each Bn has, a regularly appointed Adjt, except the 19th, in which an officer is temporarily detailed for the duty; an AAQM detailed from the line, & an assistant surgeon; & the 18th has a Lt detailed as acting ordnance officer
The number of extra duty men is not excessive Four men of the 20th Bn are improperly detailed as a permanent guard at Mr. Lyon's house; they should be relieved at short intervals As artillerists: It is not probable that these troops would do good
service in an emergency, on account of their almost entire want of practice in or out of the presence of the enemy; as Infy, scattered & broken up as the Co’s now are, they cannot be considered efficient. Two or three Co’s of veteran artillerists would be a much more reliable force at the guns on the lines of Richmond, & these Bns organized as a Bgde of Infy (1,429 bayonets), if it can be legally done, would make a handsome reinforcement to any army, in the field

1/9/65 the Hvy Arty & Reserves were organized into one Bgde under Lt Col John C. Pemberton. Also, Col Stapleton Crutchfield assumed command of the Chaffin’s Bluff Arty Bgde, to which the 19th Bn would soon transfer. With Maj Cary on leave Capt Chalmers of Smithfield took temporary command of the 19th Bn. On Jan 29, 1865 the 19th Bn was ordered to abandon the intermediate lines & report the next day to Chaffin’s Farm, east of Drewry’s Bluff.

http://www.iwchs.com/bits_of_history.html
In early Jan 1863 the 19th Bn was reduced to four Co’s. The Btrys surrounding Richmond were divided into two sections, the 10th & 19th Bns manning the 1st section on the eastern side of the city. In May Maj Atkinson was promoted, & Dr. N R. Cary was elected to command the 19th Bn. Most of the summer was spent in the continuing construction of the Richmond’s defensive lines & providing guard details for prisons & Gov’t facilities. Col W. H. Stevens’ inspection reported that the work at Btrys 1, 2, 3, 4, 8, 9, & 10 was in good progress. The 10th & 19th Bns remained near Richmond for the rest of the year, each manning 63 guns with seven men to a gun. “A week before Christmas, President Davis, Gen Lee, Gen Ewell, & Col James Chesnut inspected the Arty fortifications ringing the city. Mary Boykin Chesnut noted the event in her famous diary.”
The Hvy Arty would become very active in 1864. 1st, on 2/4/64 thirty men were reassigned from the 10th & 19th Bns to the Engineer Regt. On the 20th, Capt Chalmers of Smithfield was ordered to exchange his Springfield muskets for an equal number of Miss Rifles. On March 1, 1864, 19th Bn was ordered to proceed immediately to the intersection of the intermediate lines with the Brooke Turnpike with rations on hand & 30 rounds of ammunition in their cartridge boxes. The movement was in response to the Kilpatrick-Dahlgren raid on Richmond. Afterwards, Col Stevens reported that the Arty had been “handled exceedingly well”. In May 1864, the 10th & 19th Bns were shuffled around to meet the rumored advances of Gen Butler.
In late May 1864 Col Archer Anderson in his inspection of Richmond Arty defenses stated “As Infy, imperfect . . . : as Hvy Arty good.” However, more drills were ordered, & part of 19th Bn was ordered to the Mechanicsville Turnpike & the Intermediate Lines. Also, the Btry on the Williamsburg Road was transferred from the 19th Bn to the 10th Bn.
In June, with Grant beginning to lay siege to Petersburg, portions of the 10th & 19th Bns Hvy Arty were ordered to the Mill & Varina roads & to the exterior lines around the New Market road. On July 30, 1864, below Petersburg, was fought the Battle of the Crater, which caused much excitement among the Hvy Arty. The 19th Bn was issued two Coehorn mortars in Aug, which they placed between the Central RR & the Meadow Bridge Road. In Nov 1864, 19th Bn was at Btry # One, just southeast of Richmond.

On Jan 1, 1865 the Hvy Arty men were scattered & they were no longer acting as a unit. On Jan 9, 1865 the Hvy Arty & Reserves were organized into one Bgde under Lt Col Pemberton, who after exchange had resigned his commission, but, remarkably, in 1864 accepted the rank of Lt Col with command of the Arty defenses at Richmond. Pemberton’s four Hvy Arty Bns had strength of 1002 men.
Also, Col Stapleton Crutchfield assumed command of the Chaffin’s Bluff Arty Bgde, to which the 19th Bn would soon transfer. With Maj Cary on leave Capt Chalmers of Smithfield took temporary command of the 19th Bn.
On Jan 29, 1865 the 19th Bn was ordered to abandon the intermediate Lines & report the next day to Chaffin’s Farm, east of Drewry’s Bluff.
In the first two months of 1865 more than half of Pemberton’s cannoneers deserted, died, or had been reassigned. Such was the decline of the Confederacy. The 10th & 19th Bns remained at their positions in the Richmond defensive line & at Chaffin’s Bluff with little movement until Richmond was evacuated on April 2, 1865. Night blindness was becoming a problem due to the lack of nutrition.