regarding your first question,
if your on a Mac, use iPhoto to transfer photos/videos from your iPhone to your computer.
if your on a PC, go to 'My Computer', select/double click on your iPhone from the Devices menu , and select and drag your photos/videos to a folder that you want (I apologies if i am wrong, but I'm a mac guy).
both methods will transfer over the raw video (no compression), so your videos will stay 720p HD.
regarding your other questions, I don't know.