Rabbits can have pumpkin. However, you don't want to give too much as any new food can cause problems if given in large amounts. Start with a tiny piece and see how your rabbit tolerates it. If she does fine, then you can increase the amount. Since you probably aren't going to be giving pumpkin as part of the regular diet, stick to small amounts.
Canned pumpkin (not pie filling) is good if your rabbit is having runny poops or is constipated. It is has lots of fibre and can help regulate the GI tract.
You can give it as a regular treat, just get your rabbit used to eating it before you give large amounts.
Yes. Rabbits can eat Pumpkins and other vegetables
yes
see Davidvella.com.au
Pdf on rabbit care