First scenario:
I'm not blowing the whistle as soon as the ball hits the net. I'd be doing it pretty much on the kick off restart.
Second scenario:
Assuming it's neutral AR's that would have been covered in my pre match. If I'm in a credible position to give a decision I want zero involvement from my AR to exactly avoid this type scenario, my instructions are that I'll stand or fall by my decision. If I've not got a good angle I'll be looking at my AR for help which will be very clear to them, in which case they are flagging for the penalty and I'm going with them, most likely after a quick consultation around confirming the offence and the sanction.