Default [Q] tablet as car system connected to phone

Hello,

Ive got a quick few questions.

My headunit was recently stolen from my car, and Im considering replacing with a tablet, possibly a google nexus 7 or any other seven inch tablet.

My current phone is an LG optimus pro.

I want to be able to buy a wifi tablet, and stream everything from my phone to it. Pandora, gps, and so on.

The easiest way would be to tether, but I bave unlimited data on att and would prefer not to lose it.

Can anyone highlight any methods for either remote viewing the phone on the tablet, hiding the stream from att, or any other method.

Im not opposed to setting up a wireless local network in the vehicle if it would allow me to simply stream audio on the tablet, and use the gps.