Android tablet to control phone whilst in car?

[AC Question]

I have updated my car headunit to a sony MEX-N5100BT which is controlled by a nexus 7 tablet install and the sony songpal app, however I can't use the tablet screen to make and receive phone calls which is annoying.

Is there any app which would allow me to control my phone via the tablet (mirror) or even just the phonebook and call functions?
I have a MiFi unit so it could be either by WiFi or bluetooth.

Thanks!