Oh what a Pandoras box you are opening.
There's not a simple answer to your myriad of questions.
You can start by breaking them down into simple groups.
For British infantry you either have early or you have late.
Early (Peninsula) will mostly mean Stovepipe shakos. Late(r) (Waterloo) will mean Belgic shakos although not everyone.
Plus you may/will have Highlanders in kilts and feather bonnets although not all Scottish regiments will be Highlanders.
All will be in red jackets except for some rifle armed units who will be in dark green.
If you are doing Peninsula you may have some Portuguese in dark blue or brown jackets. Not required if you are only doing Waterloo.
If you are going the whole 10 yards then you will also have some German units some of whom will be in red and some won't. Also some Dutch and Belgians (I pass on their colour schemes).
Artillery will fairly simple i.e. dark blue jackets.
Cavalry, well cavalry will be a particularly long answer.
Good luck.
Best to ask a playing friend as to what he does.