Here's a form that another rehoming centre (not in your area) uses to assess suitability. It gives a few clues as to the type of questions you might be asked:
http://www.hoperescue.org.uk/sites/default/files/forms/Hope%20Rescue%20Adoption%20Interest%20Form.doc
(Note that the link goes to a Word document. It will open in Word, or whatever other word processor you use which, if I remember correctly, is probably AbiWord).
Don't get freaked out about the possibility of a few questions though. As long as you can show that the dog is going to a good home yopu should have no problems.
This link, from the website of the centre where your doggy is, is well worth a read:
http://www.assisi-ni.org/taking-on-a-rescue-dog/
(If you make it clear that you've read and understood that information you'll probably impress the staff!)