To keep everyone on the same page, (very simplified) the unit breakdown to follow. I haven't included anything lower than company, as they are too small to be of relevance in major engagements and rarely acted independantly. Numbers vary wildly, and were effected by casualties, many units did not replace casualties and were folded intop other units when they got too small. These reflect Infantry units, Cavalry and Artillery were a little different. That being said, here is the dirt:
1. Company: Commanded by a Captain, made of platoons (led by lieutenants) and having from 60 to 200 men.
2. Battalion: Commanded by Lieutenant Colonel, made of companies and having anywhere from 100 to 800 (or more) men.
3. Regiment: Commanded by a Colonel, made of regiments. Startin here and continuing, numbers get funny (for the Civil War).
4. Brigade: Commanded by Brigadier General, made of regiments.
5. Division: Commanded by Major General, made of brigades.
6. Corps: Commanded by Lieutenant General, made of divisions.
These were the operational units. Armies and Army Groups were too large to be of tactical significance (I am a details man). Like I said, numbers are hugely variabel, as are commanding ranks. You cann have 200 people in a company, but fewer than 200 in a regiment, and so forth. A lieutenant can command a company given need, an major can command a battalion, and so forth. It certainly doesn't help to simplify the study of history.
1. The Henry was a good gun, better when they started making the shell casings in brass instead of copper. As it ws difficult to get ammo, I wouldn't have wanted to carry one during the war unless I was certain I could get ammo when I needed it.
If I had been a regular infantryman, I think I would have preferred the .58 caliber 3 band Enfield. I know some reenactors who have them and the rifle is incredibly accurate for a muzzleloader. They are easy to clean and fired a standard minie ball so getting ammo wouldn't have been a problem.
The scariets muzzleloader of the time was the Whitworth rifle, which was used by some Confederate snipers. I know someone who has a replica and while it is stunningly accurate, the barrel has to be cleaned every few shots or else the odd shaped hexagonal bullet can get stuck in the barrel while loading.
As an individual soldier, I would take the Henry any day,
maybe one of the breach-loading carbines like the Spencer if the Henry wasn't an option. If I had to equip a unit of any size, the 1861 pattern Springfield rifled-musket would be my choice. A relativley standard round size, robust and solidly built, interchangeable parts (more important than one would initially think) and domestic (easier supply).
On the subject of uniforms, it helps to remember that as the Southern States supplied their own militias regionally produced clothing, the "uniforms" weren't all that uniform. The "Washington Artillery" from New Orleans wore dark blue uniforms as did a number of other units, at the outbreak of the war, which lead to a number of problems in the field. Even after units had swtiched over to grey, there wasn't a uniform color of grey used univerally throughout the south. Even Northern state militias had differences in uniforms. The best thing about this now is that it is nice for wargamers so they don't have to paint a thousand copies of the same uniform.
Totally. Like I mentioned, the variation in uniforms was astounding. No standard led to even friendly-fire situations early on. Like everything else in the war, there was no way to standardize as getting men into the field was more important than standard.