id prefer the quality 
thats good, buy cheep buy twice as they always say.
as for the bolts yes you will need longer bolts,
think euro car parts do some decent ones for not too much. also think they sell the spacers theres quite a few people on here with 20 mill spacers on and i think they look good. once i get my car lowerd i want either 10 or 20 mil spacers, maybe 15 mm but i dont know if you can get them. sure that someone will post a picture with 20 mill spacers to show you what it looks like though.
edit: no euro car parts dont stock them anymore, unless i just cant see the woods for the trees