I did this. I think your only option for single din flip out screen is the pioneer one - not cheap tho.
I don't think kenwood or any of the other major players seem to do them anymore.
It was about £350 with another £300 if you also want the satnav for it (a separate unit hidden behind the dash).
All that was needed was the unit and the fascia plate - otherwise just plug and play.
Even works with my mfsw buttons (not the phone buttons tho - just volume and change track rocker switches).
Yes, screen blocks the air vents when flipped up. Hasn't caused me any problems.
Just switch them sideways and th airflow mostly misses it.
Have to admit tho, the few times I have had the heater blasting as hot as poss, I have either closed the screen or switches the centre vents off. Was told it should be fine, but I'm reluctant to blast it with hot air all the same.
Often had the aircon going flat out with centre vents open, vents angled sideways - no problems.