Answering for OBR:
a) Ball is dead for being thrown into the stands. Award R2 home. Next batter is up with two outs. 7.05 (g)
b) This situation isn't specifically covered in the rules. I don't have my (outdated) J/R with me but my first impression is that the ball stays live since 7.04 (c) specifically mentions a fielder falling into the stands or dugout and not stepping into it. This is not catching a fly ball situation so I realize 7.04 (c) may not exactly apply but that seems to me to be the intent. That's my SWAG anyways, I would be glad to be proven wrong.
