The runner is already in possession of the ball. As long as he has possession, it's a TD once the ball crosses the line. (Note: the player's head can cross the plane and the ball can be ruled down at the 1 yd line if it doesn't cross before the player is tackled.)
A legal catch requires a landing with both feet in-bounds. Technically, the ball "broke the plane" in midair before it got anywhere near the receiver.