Fire zone appears to be 8743-8780 potentially up 8790 based on what I have seen during testing, logins, and keyups by radio techs/consoles. There is a handful of encrypted talkgroups in that zone.
The only talkgroups from BWI/MAA that will be potentially on the P25 system is the BWI patches that are on the AA P16 system (BWI Disp, Tac 1, Tac 2). I don't see any reason for MDTAP patches. All AAFD radios already actively use the MAA system so I really don't see the need for that patch but there probably is a reason for it.
It will be interesting to see if MSP Barrack P/J Annapolis/Glen Burnie is patched backed to the AA system as it is now on P16 and all other new statewide county systems. As of now, there is no indication of a patch. But if it happens, I will bet 100% that it is encrypted even though they are in the clear on FIRST.