WoW!! An 18" Roto Tom; wished I still had mine...just because.
Yes, unscrew the whole assembly and take the old screw to your local hardware store and find a long bolt with the same thread size and length. I'm trying to remember what it looked like but I think it is a carriage bolt. It will be a round bolt not flat on one side like the one you have. But who cares??
Well...I don't think so. At one time I had a full set and don't remember any bent bolts. It probably needs to be replaced but if it works for now, I guess you can use it that way for a while but at some point I would replace it.