What made you conclude that the seeker head survives an explosion? Provide your source please. The proximity fuse would rip apart the seeker head just like it would its target.
AMRAAMS are unlikely to have kill switches. But F-16s can certainly have them. Degraded radar performance is certainly possible.
Thus the need to switch to local + Chinese platforms in the future.
To down a helicopter would not be considered a kill to be proud of by any professional fighter pilot. Even if t was PAF that downed it thinking it was a fighter jet, it would never publicly try to claim "credit" for it.
Looks like the second R-73s seeker is in the background top left corner. That's the one that was found lying next to the crashed Mig. Most of the rest of the body of the missile seemed to have burned up.