You can run 6" Infinity Kappas with a spacer up front(not sure how big the spacer should be. I forogt, but i'll go test some out). You can also run 6" Kappas in back with I think a 1" spacer. You should be able to find a spacer matching your interior color at your local audio store.
MB Quarts are good for the price. They sound really nice IMO. They should fit w/out help. Might need to check into the back doors though. But I think it should fit w/out a problem.
Also, you need to mount the cross over somewhere. I haven't put a cross over in the door before, so I don't know if it would fit. Also, you might need to cut holes for the tweeters. Either in the door pod or door panel.
Also, if you do get an amp, get like a 400watt so you can run all the speakers and the sub thru it.