Upvote:2
A multiple entry visa will usually be granted after a number of successful visits on single-entry visa (no overstays or similar incidents). This happens automatically when they consider your application. While it is possible to request a multiple-entry visa in the form, this would be unusual to be granted for a first-time visitor.
I'm not aware of special rules for clergy. The visa form has both a "cultural" and "other" check box, one of those would seem to fit.