Boeing calls it a 747-200B, but it can only be classified as a VC
-25A because it has been so heavily modified.
AF1 has plenty of protection from missiles. It has Disco balls above each engine (on the pylon) and under the APU. Other systems aren't as apparent from the outside so I don't know about them, but if it has IR
protection one can be assured that it has radar. Also it is flown by the best pilots in the USAF
Any attempt to attack AF1 would be suicide, one can only imagine even if AF1 turns down the escort, that they aren't at least following a bit behind, just in case. And the USAF
is probally on call if need be.
At worst, you screw up and die.