I don't know about the size of the screen, but you won't see the nav maps from your phone on the screen unless you add an aftermarket module that allows for video in motion to be over ridden.

I just saw this post (actually first time to the forum) and I've found several aftermarket solutions to adding the backup camera that are a little less intensive in the installation. https://navtv.com/products/NTV-KIT368/volvo-cam-12.html , This is the most expensive which you might as well go to th...