Yes, you must apply to go. My parents have done so. I laughed and asked my mother why you needed to apply, why not just go. She said they needed to make sure that there was enough room for everyone!
She also said that applications involved how many years of service and what privileges one holds are taken into account. So this seems to be a consolidation of the uberfaithful.
As far as just any old person attending, I don't know how they would stop them, but I'm sure they will have some gestapo tactics in place.