As to the use of a clansman's badge, like it or not, there is no automatic "right" to wear or display the same. In Scotland the crest, motto, and buckle and strap devise are technically and legally the property of the chief. As such he has the right to control its use, and to say who may--or may not-- wear the badge of a clansman. It has nothing to do with your surname, and everything to do with the good humour of your chief.
A very nice summary, Scott.

T.