Yes you use a hole cutter with a drill. A hole cutter is basically a saw blade twisted into a circle. Make sure you know what you are doing before you attempt to use a drill though. If you have to, have an adult do it for you.
Like a screwdriver without the point? And?
I don’t understand what you mean, but here is a picture of a hole cutter.
You can get them in different sizes so that you can get the size you want and use that to hollow out an area to put something in there for weight. You could possible also get one that is the size of an oring and use that for response if you decide to put a bearing in or something.