Does she have an unpleasant odour in her mouth?
Not sure why your vet would suggest dental kibble or any type of kibble for your cat when she has red and inflamed gums. Anything hard against her gums will injure them more. At this point I would suggest wet food and steer clear of anything that she has to crunch.
I don't understand the logic of pulling 5 teeth and leaving the rest. That is what the vet did to my Papillon.....they left 3 teeth. Within one year of the first surgery, the remaining 3 teeth were removed to the tune of $900. The vet that did her first surgery offered to do the second for $400 but he wasn't my vet and I didn't feel comfortable with him.
Definitely shop around. You can call a few vets and just ask over the phone for an estimate.