When Zissou had fleas I used Diacetomous (sp?) Earth on her. Its about 15 dollars for enough to last more than one house and more than one cat. It is not chemical, so it can't possibly hurt her except maybe a little sneezing because its the consistency of powdered sugar and gets in the nose a little.
I definitely agree though if you want the chemical kind NEVER use the stuff they sell in pet stores / grocery stores. It can kill them, and the shampoo we used when we didn't know any better make my heartbeat irregular for a couple days. I can't imagine what it did to her.
I also feed wet and dry. She gets iams kitten dry as her snack and then wet food once or twice a day. I just ordered some Merrick and we are going to try that for wet. I am probably going to stick with the iams kitten dry for now though, since it isn't much of her diet and she LOVES it.
Someday I might switch to all wet. But not today.
As long as your cat is getting not just dry, it's fine.