Fan interference questions

[bsaucer]

R1, R3, No out. R1 runs toward second on the pitch. R3 holds at third. Batter hits fly ball, which would have been caught, but a fan reaches into the field and interferes. In each case, where would you place the runners?

Case 1: F9 attempts to catch ball near the right field fence.
a) R1 stops halfway between first and second.
b) R1 reaches second.

Case 2: F3 attempts to catch foul ball near a fence close to first base. F4 covers first, F6 covers second.
a) R1 stops between first and second.
b) R1 reaches second.

In case 2, can you assume that an appeal would have been made at first base, and call R1 out? Or must the appeal be made during the next live ball? If R1 is awarded second, should he touch first base first?