I think what you're doing is fine. :)
The door thing is really only something you need to do when you're trying to enforce strict order. This would be necessary with the "give an inch, take a mile" sort of dog. It sounds like Kat knows her place and can handle a little latitude.
Same thing with the couch. As long as she gets off without a fuss, than it's obvious she knows her place and is fine with it.
It sounds like you're doing a great job with her! :D