As a prior service AF who is switching to become an Army 68W, will I have to go through Army BCT? Will my rank drop?

Yes, you have to re attend Basic. The Army only recognizes IET schools from the Marines and prior Soldiers. As for the rank, you'll have to negotiate that with the recruiter.

How long have you been out? If you only have a short break in service you may be able retain your grade, but its tricky with guard and reserve due to TIS/TIG calculations. The recruiter will request a grade determination when they build your packet, so they will need whatever training records you have.

Full disclosure, prior service do not get the same MOS choices that first term applicants get if you plan on going active duty. There is no guarantee you can reenlist as a 68W regardless of your experience. However, you can enlist to get your foot in the door then reenlist for 68W- if there are training seats available. Or, you can enlist as a 68W in the reserves, you just have to find a unit with a 68W slot available.

Is your Paramedic an NREMT-P that is the only thing that the Army will recognize? But as for a straight 68W I can't remember you may still be required to have the NREMT as that is the current requirement, I can't recall exactly. As for flight medic if that is your goal it will be a lot easier to obtain if you are NREMT-P as it is of no cost to the Army. As for rank and Basic You mostly likely will end up going back through basic again since The Army only recognizes IET from the Marines and prior service like SFC Hasbun previously said or if you attended ROTC. Rank is negotiable with recruiters.