Interference question

[rafking]

This was from the baseball forum, so I want to ask it on softball to note any difference. Fed.

"Fed Rules. Bases loaded with two outs. Batter hits a high popup in front of the plate. Runner on third interferes with the catcher who is attempting to make the catch. The ball falls untouched and ends up in foul territory. My question is who leads off the next inning? The batter who hit the popup or the next batter in the lineup?"

My follow-up questions:
2) Just to clarify: If only one out in above situation with uncaught interferred fair ball that went foul, then is runner out, and batter awarded first base on fielders choice?

3) (depending on how the question above is answered) Is there anyway that a batter-runner is called out when a runner interferred thus leaving the runner safe?

4) In reverse, when can we call the lead runner out when a batter-runner interferred?