A:
It all depends on the body of water your fishing in! Some colors work best in one lake,pond,river! But will not work as well in an other location, like an other state, or provinces! Here in Canada, where I fish, the silver has always been a go too color, but five miles down the road, the pink body, silver blade works better! Just get the major colors and you will be set! Get the gold,silver, silver yellow, gold silver,pink if you can get it. Also get different sizes, from the 1/32 all the the way up to the 1/4 oz..
As for dressed or undressed, I find that I have more success without the fly, that also depends on your area.
All in all, get a good selection for different areas, they all work very well!
Tight lines,
and be safe!