Yes, you can.
It depends on the distance of the buildings

Yes, subject to compliance with the conditions of category A3. See Bazl website, open cat.

Yes, I also fly this drone with the A1/A3 certificate from EASA. Comment on Mavic 3pro: The quality of the camera is fantastic

Yes you can, but then as a C2 drone with 150m distance as it is over 900gr

Thanks - I've decided in favour of the mini 4 Pro after all - hope I don't regret it :-)