Most of your questions would be answered in "Hood's Texas Brigade, Lee's Grenadier Guard" by Colonel Harold Simpson. Other books to check out would be "Hood's Texas Brigade" and "Don't Hurry Me Down to Hades" both by Susannah Ural. One more is "First Texas Regiment" by George Todd who was captain of Company A of the regiment. Of course, there are others, some specific to a particular battle.

Mustered, where and when?
The three Texas regiments were mostly organized in Virginia. Many of the companies traveled east individually or in company of one or two other companies. The three regiments were brought together in late 1861 at Dumfries, Va. The 18th Georgia and Hampton's Legion of SC infantry was added later. In late 1862, the 18th and Hampton's Legion were transferred and the 3rd Arkansas was added to the brigade and remained until Appomattox.

What would daily life have been like?
Dull and routine to unmitigated terror in battle and everything in between.

How were officers and NCOs selected?
As a general rule, NCO's and Field officers, major and down, were elected.

Food?
Often inadequate and almost always lacking in proper nutrition.

How was the brigade moved to the east? Trains, marching?
A combination of trains, marching, and sometimes steamboat.

Not much help, but it's a big story which will acquire a lot of research.
Best of luck. js