I have been reading some literature about old-time music and they refer to the banjo accompanyment as being "claw hammer style". Can anyone describe that.

By the way, in reading this stuff I am getting interested in the banjo (passively for the time being, I hope). Here are some questions for banjo experts

Do the five-string ones come in different sizes, and if so do the sizes correspond to different tunings, or just to acoustic differences like the difference between a dreadnaught and a parlor guitar.

What other kinds of banjos are there besides five string? Actually I recently saw a film of somebody playing a fretless banjo.

Thanks,

Murray