the other thing that i use to dye nylon is kool-aid. it works really well, is easy, cheaper and doesn't have that dye smell (you end up smelling kool-aid instead)and you can get some pretty funky vibrant colurs as well. i have used it on white nylons, and bras and panties that i have made.
just boil a pot of water, add a dollop of vinegar to help set the colour and of couse the kool-aid. add your wet fabric and stir until you reach the desired colour. the water will turn clear when all the kool-aid is absorbed. rinse and dry.
if you dye over another colour, expect that it will affect the final result. i probably wouldn't use green over the brown because i think it would be a swampy colour. unless of course you like that.
as far as the second question goes, from one boob-a-lious babe to another, it depends on the look you are going for and how comfortable you are. some people won't like you in it and of course some will. what kind of attention are you looking for? i have a very low cut shirt that i will wear to clubs but i wore it once to a dinner out with friends and immediately realized my mistake. i asked my husband to get a sweater from the car after i noticed the stares from the men and the glares from the women. normally i don't change but was uncomforatble enough (and cold enough lol) to think it was a good idea.
so just go ahead and make it!