[wurls]

Go with 4 Infiniti speakers hooked up to the head unit of the deck for power. 2 rear speakers, and the two larger ones in the bottom of the door. Leave the top two tweeters in the doors unhooked, you don't need them when you have 4 good speakers.
You don't need an amp after that for an install, because the interior of the car is small...unless you want bass. Then you're talking subs, an amp etc.