Assuming winning/losing in OT is 50/50...
Kick after first TD:
Lose game (miss kick then miss 2pt convert, miss kick then make 2pt convert and lose in OT, make first kick and miss 2nd kick, or make both kicks and lose in OT):
(.05)*(.48) + (.05)*(.52)*(.5) + (.95)*(.05) + (.95)*(.95)*(.5) = 0.53575 or 53.6%
Win game (miss kick then make 2pt convert and win in OT, or make both kicks and win in OT):
(.05)*(.52)*(.5) + (.95)*(.95)*(.5) = .46425 or 46.4%
2 pt convert after first TD:
Lose game (miss 2pt convert then miss 2pt convert, miss 2pt convert then make 2pt convert and lose in OT, or make 2pt convert then miss kick and lose in OT):
(.48)*(.48) + (.48)*(.52)*(.5) + (.52)*(.05)*(.5) = 0.3682 or 36.8%
Win game (make 2pt convert and make kick, make 2pt convert and miss kick but win in OT, or miss 2pt convert and make 2pt convert and win in OT):
(.52)*(.95) + (.52)*(.05)*(.5) + (.48)*(.52)*(.5) = .6318 or 63.2%
Holy ####. It's not even close. I stand corrected.