You’re correct about the job being much more than one might guess. As Art mentioned, a regimental adjutant was a colonel's chief of staff. As such he coordinated all staff activities and operations, answering directly to the regimental commander concerning current status and any issues that he needed to know about. He was responsible for all orders and communications being issued or received at headquarters, as well as retention and care of regimental papers, rolls and orders.
Regardless of where they originated, all orders received -- general circulars, special orders as well as orders specific to the regiment -- were delivered to him to be read and distributed as needed. Some adjutants keep a letter book to reference communications issued by the regimental commander. He was also required to complete, copy and forward regimental strength reports, inspections and company rosters on a regular basis.
Anyone wanting to know what was really happening (or about to happen) would have been wise to speak with the adjutant.
Try to catch him when he wasn't occupied with business of the day. From dawn to dusk, the adjutant managed all routine activities concerning regimental headquarters. As head of the colonel's personal staff, he selected or hired any clerks, cooks, couriers, laundresses, teamsters and laborers necessary for daily operations. When orders came to break camp, the adjutant directed dismantling, storage and transportation of all headquarters property, public and personal, to the new location. We might expect this to include the regimental colors. If the colonel was busy or delegated the responsibility to him, the adjutant also selected a suitable place to set up the new headquarters. Whoever made that decision, getting HQ established and back in operation was his job.
A regularly appointed adjutant served at the rank of 1st Lieutenant. If he happened to be absent or incapacitated, the regimental commander selected a 2nd lieutenant to act in his stead. A 1st lieutenant received $90 in regular pay per month, $10 more than a 2nd lieutenant's pay. To compensate officers of lower rank serving as acting adjutants, $10 per month was added to their pay, prorated for a partial month's duties.
Adjutants had be men thoroughly acquainted with preparation, processing and delivering formal documents. He also needed to be organized, efficient, able to make quick decisions and comfortable with sums, so we often find attorneys, accountants and senior clerks in this position. Apart from his regimental commander, whom he often represented, this officer was among the most visible in the command. A regimental adjutant was the only staff officer who might ever be elected or appointed to a command position. Several Confederate colonels had been adjutants at one time.
Obviously the adjutant had more than enough to keep him busy, quite a bit more than simply shuffling papers. I'm sure others who know more about the adjutant's job can add to this list. If anyone knows of a complete list of duties, please pass that along.
If you're interested, a couple of recent books will provide further detail on Confederate adjutants and their duties.
The Headquarters Diary of Edward O. Guerrant and Stonewall's Man: Sandy Pendleton are two that come to mind --