check out
www.darksidesubs.com should give you a good idea of fitments.
for audio, depends on how far you are willing to go. The premium option is to actually custom fit and mount 8'' boxes that go behind the rear of the seats, however since thats top dollar and requires modification the usual option is to mount a 10'' or 12'' in the center section or 2 8'' 's on the sides. I've seen some people remove their spare tire and modify the back wall and lay a sub flat, but thats personal preference.