Rabbits can eat small portions (a bite or two now and again) of some fresh fruits as a treat but, although grapefruit is not toxic, it isn't recommended. See the related question linked below for more information.
There is an extensive list of "possible safe plants" on www.homesteadingtoday.com, in the Raising Rabbits for Profit group, in the DRAFT Safe Plant List for Rabbits article.
Yes, They like a bit of fresh fruit or veg, but don't overdo it or they'll get diarrhea.
yes but in moderation
no they cant
No. They eat seeds.
Apple seeds are toxic to rabbits and many animals. Apple seeds contain a cyanide compound -- this is what makes them poisonous.
yes because they have seeds in them and they are bad for them.
Yes.
cottontail rabbits eat dandelion grass seeds and berries
Rabbits can eat pumpkin seeds. Raw seeds are best. The seeds have antifungal properties which are beneficial for rabbits, and there is some evidence to suggest they may also help rid rabbits of worms.
seeded grapes have seeds in them and seedless grapes don't have seeds in them.
Birds eat them and defecate the seeds elsewhere. That's why one often sees wild grapes growing on fences.
cottontail rabbits eat dandelion grass seeds and berries
Green grapes may have a slight crunchy sound to the skin when you eat them. If they have seeds, these may crunch as well. The rest of the grape will be soft.