Like every SWU, it's never official. Don't expect official guidelines. It's supposed to be a retention plan.

Yes, only available at official TM stores, not availble on dealer stores.

Just walk in and ask for yourself.

Yes they can, but you can always try again with different staff or at different Tmpoint.
After all, SWU is like a secret offer for existing users to stay on and not port to other provider.