There is a lot of cat people here to give you advice!
Cats do not like vets.....so your cat will probably never stop hissing. I know you can give them a drug that relaxes them for the visit. If she is a great cat at home I wouldn't worry about it. As for the stitches, I bought a bitter spray from my vet that tastes really bad, spray the area. Whenever you do something with her, wrap her is a taught large towel to help keep her contained, cats can put up a huge fight!!!