Hi John, pretty much any DD will work but there are varioys 'issues' you face
I am not sure if the factory BT works with aftermarket HUs as I never used it but most have their own BT phone control anyway.
You can retain the birdview but you will lose the sound, there are options, you can splice some wires and then choose satnav or music, not ideal but it works, ok wire it into a seperate little speaker.
There are lots of very good theeads, make a cup of tea, set aside an hour and have a good read