Some of the answers I wish were a little different. For example: I would prefer to select the option that one must have no violent felonies, or felony drug charges to carry, and be free of misd. drug crimes for 1 year.
I think the only disqualifiers should be the same ones as the right to vote with the exception of age. (Even those who have served prison time deserve the right to self-defense). Of course, that might encourage states to toughen voter requirements, which I wouldn't mind one little bit.