I would take the paper work. Some vets work with the humane society and may give a discount on an exam, but they usually require the paperwork to make sure the rabbit was adopted. The paper work from the humane society also has info on when she was spayed (if they did the surgery), and medical treatment given at the shelter and the known history.
Many questions to ask are related to making sure the vet is rabbit savvy. Since many vets don't know much about rabbits, it is important that you can make sure your vet is good and knows rabbits.
Other questions tend to be about your rabbit and if you have questions. If you do have any concerns or questions, write them down before you go so you can remember them.
The vet will have questions for you, so make sure you know the brand of food you feed, type of hay, kind of litter/bedding and other things about how you care for your rabbit. Write them down if you need to as well.
Be sure to bring your rabbit in a carrier, most vets require a carrier for safety. A towel in the carrier is good and putting some hay in as well is also good.
