Got my head unit installed yesterday - as was mentioned before the E90 CANBUS harness allows a direct plug-and-play. I'll do the backup camera later and currently the GPS antenna, new mic, and USB cable are just routed through to behind the glovebox. However, I can confirm they all work as intended.
So my unit actually did *not* come with extensions for the screen attachment points even though they were referenced in the documentation, but when I position the screen correctly (the highest position so it doesn't block the HVAC controls) it doesn't mess with the ribbon cable or the dash trim. It's a pretty perfect fit and the wider screen on this unit prevents you from seeing anything behind it.
I'm really, really happy with it. Other than being a fingerprint magnet it works really well. It sounds incredible - I like the flexibility it offers with the equalizer and all of its options. Currently my steering wheel controls don't work so I'll have to troubleshoot that and code out the SOS error but everything else is incredible. I don't have PDC so can't comment on that and the CANBUS harness here gets rid of the factory gong and replaces it with an annoying beep that plays through the speakers
I've heard that's the case with every aftermarket Android unit unless you get the other harness and wire it yourself.