Legally no but otherwise yes.
No, you must be 16, have at least a drivers permit and its a street legal vehicle that is appropriately registered.
on your driveway
yes
Yes, completely safe. If your 8 year-old can ride a bicycle, he/she can ride a dirtbike.
13 to 14 years old
yes
Yes
no
a bike.
Yes, but good luck fitting on it ;)
I think any one can easily ride a pocket rocket. They are extremely slow and have almost no power. They are also very easy to ride with a twist and go operation. So a 9 year old would be fine on a pocket rocket.
they are generally illegal most everywhere to ride at that age... and i am a BYU fan!!