I've been able to rip the CSA to shreds in firefights as the union if I abandon non-forested defensive positions and focus on the major ground. I feel that buford's cavalry is not able to really complete its objective of holding McPhereson's ridge in a historical way, but I can pull them back to any forested area and use them to delay like they were intended.
I agree that cavalry needs to hit from a flank or at least charge in between reloads to be effective. However, in my recent playing, this actually does seem to be the case. Others are reporting different results, of course.
Artillery targeting - with the pseudo 3d terrain (which is fine), feel free to spoon feed me on targeting. Like, if I target an enemy artillery and it switches off to shoot something else, I wouldn't mind a message saying why, or a way to force them to shoot what I asked them to for say, 2 minutes. I've played the game since release and I still don't know where to put my artillery in several situations.