NEX 5N Video Tips?

Thanks a bunch for this! I can see how in a controlled interview environment going fully manual would be beneficial. Few questions if you wouldn't mind indulging a noob:

• I've read shutter speed should be set roughly double the frame rate. Is there a reason for this? So for shooting at 24p a setting of 1/50 would be best, wouldn't it?

• Wouldn't I want the aperture as wide open as possible (f3.5 on the kit lens) to get as much of the background out of focus? Or would having it set at f4 or f5.6 allow for subject movement without them going out of focus?

• For handheld running and gunning, what would you suggest for shoot mode? Program? Aperture Priority? When I'm not doing interviews I often have to follow multiple moving subjects.

Many thanks!