yeah man, you wont be disappointed. lighting is the MOST important thing in photography. and most of the time natural lighting is not good enough. even if you think it is, it can be vastly improved with a speedlights.
as for reverse lens, nope, you only need one! i use only one lens. you can get a $10 extension tube to make the magnification even stronger. and get a cheap $5 reverse ring. i got all this on ebay. but you wont get good shots w/o a speedlight, since your pictures will be almost pitch black unless youre shooting in extremely bright conditions