It really depends:
If you can answer "yes" to all of the above, pack a snack and a drink and go for it. Shouldn't take more than two hours, tops. And I'm assuming there'll be a responsible adult going along the ride.
A 13 YEAR OLD CAN RIDE A MINI BIKE AS LONG AS IT IS NOT ON A PUBLIC STREET.
Yes. If an 8-year-old wants to learn to ride a bike, another person can teach them to ride it. Usually, that involves helping to balance the bike until they get the hang of riding it.
I'm not exactly sure how big a super pocket bike is, but if the bike is too small for you to ride safely, get a bigger bike.
on your driveway
Yes
yes
THer really aren't any "shoulds" in kids bicycling - but I'd be surprised if a 9-year old didn't manage something like 2-3 miles.
No.
yes
no
as a child learning to ride a bike as a presidential candidate as a game show contestant
Yes, but good luck fitting on it ;)