Eric J. Menhart's Answers

What rights do I have, regarding rental and re-sale, as the owner of a licensed costume.

There isn't really enough information here to give you a sufficiently full answer. But, for example, if you were appearing as Ronald McDonald, a character that has been protected by McDonald's corporation, then it may be likely that you are infringing a trademark by appearing in Ronald McDonald's likeness without the permission of McDonald's to use its trademark. The same problem would apply even if you dressed a mannequin as Ronald McDonald as opposed to dressing in the costume yourself....