It uses a 3/8 drill and I use a cordless drill
yes in a home depot 5 gallon pail works great
By using it a few times, and that it have not formed any rust on it, I would believe the entire thing is made from stainless steal. When using it, make sure you use a hammer drill or something strong. It will burn out the motor of a regular drill.
It takes a lot of torque so it would probably wear the battery pretty quickly.
It is steel but hasn't rusted so if you clean it each time, I would use it for food.
I think you will know which is best depending on the product you are using it for. At high RPMs I noticed it would throw materials out of the bucket, so you may need to "feather" the trigger while mixing.
Not sure this would be sturdy enough if it was any longer. This is a great length. I'm 5'6" tall perfect with my 1/2". When I tried to mix about half of a 50 pound bag at once I had to go slowly. The shaft has some flex when you're trying to mix thick, heavy batches