1- The illegal Forward Pass takes precedence over the IW, when the penalty is accepted. (4-2-3d)
Restated, if the penalty is accepted the IW is discarded and, since IFP contains a loss of down the game is over. (See Casebook 3.3.4 SITUATION A)
2- Since the IW is discarded, 3-3-3c is not applicable.
3- The moon walk is a dead ball foul. Dead ball fouls are always enforced from the succeeding spot. There is no succeeding spot, as the game is over. This foul goes unpunished unless act is considered flagrant whereas the offending player is disqualified and then, the game is over.
4-The Try shall not be attempted unless the point(s) would effect the outcome of playoff qualifying. (8-3-1 Exception)
5- Only if the Try is necessary as in 8-3-1, would the USC penalty be enforced on the try.
If you really want to muddy the watters and test your brain, read 8.2.2 SITUATION C