Throw-In Situation

[crosscountry55]

AP throw-in, backcourt endline.

A1 has the ball at disposal for the throw-in. Nearby, B1 is defending A2 who is trying to get in position to receive the throw-in pass from A1. Eventually, A2 fakes out her defender and gets close enough that A1 reaches out over the plane with the ball and starts to hand it to A2. However, A2 never grabs or possesses the ball. She comes close, but ultimately the ball rolled partially up her fingertips at which point B1 arrives and is able to get a firm grip on the ball while A1 is still holding it out over the plane.

Q1: Does the ball become dead at any point here, and if so, when/why?

Q2: Assuming there's a whistle and ruling of some sort, what happens next?

Bonus points for defense of answer with rule citation.