Firing and loading I find useful in limited numbers for skirmishing. Otherwise the're a pain if you want troops in column.

Any infantry pose that does not work in a rear rank is a difficulty. Marching is best, but I'll take standing.

Standing is, I suggest, what cavalry spend a lot of time doing on the battlefield. Walk or trot is fine. Galloping poses are not much use, I find, though you don't always get a choice.