I assume its in the PCM, but you'd have to figure out where the IPC get the fuel sender signal from.
No, you dont have to flash the BCM if you change the PCM OS, who told you that? Just because you're running an 05 OS doesnt mean you cant put your 02 VIN in...
The airbags and everything dont tie into the PCM...thats not an issue. The 04+s have the AIR injection system on the exhaust manifold so you just have to turn that off in the tune.