what ifs (dp/flex)

[Little Jimmy]

I'm a what if kind of guy. So no matter how many posts I read on numerous boards covering the many angles of dp/flex, I still end up with " but what if this...?"). So I'm going to expose myself to some possibly obvious answers.

1. Can flex play any defensive position at any time? For example can flex start at F1 then change to F9 with no problem?

2. In the same vein as number 1. Dp in for flex(F1). Can flex reenter as F9 defensively but not offensively ( F9 still batting in her regular spot?).

3. How about this scenario? Flex in for dp( dp has one reentry). Later dp back in for flex (she drops back down to 10th). Still later flex in again for dp( dp now has no reentry). This has flex batting for a now non existent dp. Is there a need to enter a new dp at this point? Or can the offense wait until they're ready and enter a new dp in the future dropping flex down to 10th?

It's no good being dumb if you can't show it. What am I missing?