i'd do the second option that way all the speakers are powered by the same amp. it'll probably lead to more balanced sound, i would think.
and i've always been a fan of a dedicated sub amp since it will be the one working the hardest.
go for the class d amp for the sub and as for the mains i've had great experiences with both pioneer and r.f. for amps so go with price i guess.
sounds like it will be a killer setup anyways