Xoom Mount: Ram Mount Review.

AdobePhil

I have a 4G model; however, if you have the wifi model, you can tether to your rooted 3G or 4G mobile phone. As long as your Head unit supports bluetooth, you can split up the bluetooth connection regardless of whether your tablet is using a 3G/4G connection or wifi teathering.

I don't know of a way to control your tablet from your phone; however, my head unit controls both the phone calls on my Droid 2 (address book / voice dial / hang up / answering) as well as the media functions utilizing google music on my tablet (so when I press skip / pause / play / etc... it sends the command to the tablet)

I do have logmein ignition on my tablet though, so I can control my home computer from wherever I am, as well as accessing files from my home computer due to the fact that I set up an FTP and use ES File Explorer on my tablet to access them.

Gungrave

I'm assuming you have Verizon? Don't they charge extra for tethering and/or hotspot on your phone?

AdobePhil

I have verizon, yes, but if you root your phone and download a 3rd party tethering app, it's free.