A1 catches a free kick at the 2 yard line and his momentum carries him into the endzone. is this blown dead or can he run it out?

He's holding a live ball. He may run it out but doesn't have to. If the ball becomes dead by rule behind the goal line the momentum exception will be in effect and team A will put the ball in play 1st and 10 from A's 2.

By the way, I believe you mean to say R1, not A1. On kicks the team designations are K and R.

Canadian Ruling
 

Possession is deemed to be gained in the end zone. B may continue or concede a rouge, which means it is B 1D/10 @ B-35.