i'd say go w/ one shade all around. the only cars i think that can pull that off are 4 doors!
percent wise, go w/ 15%. 5% is way 2 dark, and just imagine that at night w/ no lights around u! and anything higher just doesn't seem as black? doesn't make sense, i know, but it more or less looks like a dark grayish purple if u go 35%. <plus, the tint will fade alittle, so 35% plus fading = u will hate it!
and price wise, if it has a lifetime warranty, then that price is right! i paid 200 for lifetime warranty tint!