1. I had 2 corps, 3 div, 4 brigades. I cant remember if they were 1500 or 2000. Won Shiloh handedly though. Towards end of 1st day you get 2 divs from Buell and on 2nd day, you get the rest of his army/corp.
2. I split my batteries between 10 lb ordinance and 12 lb napoleon. 10 lb is great for mid range while the 12 lb utterly devastates anything up close.
Regarding Shiloh, there's a few key maneuvers you must make to be successful:
1. Skirmishers. Put them out front to delay. Use them to flank brigades. Uss them to fill thr gaps. You get the picture.
2. Use a melee cav unit to run behind CSA lines and destroy their arty and capture supply. Takes a lot of micromanaging, but if successful, by the time you retreat to the earthworks at the landing, they'll have no arty and will be running out of ammo.
3. Know when to retreat. The map gives you hints in the form of VPs. Use detached skirms to cover retreat. Fallback just a bit at a time. This allows your brigs to cover your skirms if enemy tries to charge. Once you get to the map with the earthworks, hold the line just long enough for Buell's div to shoe up. Use them to man the defenses at first, rotating out units as they take damage. Watch for the brigades on the earthworks about to break and rotate them out before they do.