New idea for head unit

So I'm looking into using a kindle fire HD as a head unit, but what all would I need to make this possible?

Using kindle fire HD because cheap and no one is going to break into my car for a kindle.

ALSO, should I have an amp for my speakers and an amp for a sub when I get one? I've got Kicker CS series speakers in the front doors, and I'm still trying to find a matching set for the rear doors without going to another set that has tweeters. I have no use for six tweeters and all it's done is cause me headaches just having four.