I can address some of your points:

a) I've been in front of a row of charging riot police once in my life (accidentally, there were some riots At Les Halles in Paris at night and I just happened to walk through unaware of it) and I moonwalked out of there at full speed. So I will definitely avoid being too frontal.

b) I've decided to opt for a tiny pocket digital in order to be able to quickly pocket it. The pictures won't be great on the other hand.

d) I wear contact lenses so tear gas won't affect me as much (I know it sounds weird but lenses collect a lot of the stingy stuff on their surface and it thus doesn't hit your eye)

e) and f) are good advice, particularly f) is important, I'll keep it in mind at all times