Hi Everyone

I've been doing lots of research lately and keep ending up on links that lead to this forum, so I decided to join and post my question. I need advice.
My yorkie, Sky who is a little three pounder and will be 7 on April 28th, was hospital two weeks ago tomorrow for bladder stones. She had three bladder stones which required emergency surgery. She's doing well now, thank goodness, but the stones are still out for analysis and they did a urinalysis on her and found out she had a urinary tract infection. She had no symptoms and the only way I found out she was sick was when she refused food and my Kyie is a garbage disposal. She'll usually eat anything and everything. I would hate for her to ever have to go through this surgery again and pain if I could help it.
The vet wants me to feed her Royal Canin S/O until the stone analysis comes back and then put her on a food meant for her type of stone. Most likely this would be a Prescription Science Diet. For right or wrong I do not like these Prescription foods. I feel they have too much fillers and by products and are not a high quality food. Just reading the ingredients makes me feel sick to my stomach that this is what my vet wants me to feed her.
Before Sky got sick I always fed her a mixed diet of all natural dry food (recently started her on Blue Buffalo which she loves) and every so often I would give her cheese, chicken, rice, turkey, etc... Normal human food. She got into this habit because when she was a puppy she was four months old, didn't even weight a pound, and refused to eat so my vet told me to feed her what I can (actually he sent me to Boston Market, lol). I try to balance out her diet.
I guess my question is this. I really do not want her to eat the Prescription Diets because I feel they are not as good quality wise as what I feed her now, but I don't want her to get stones again or a urinary tract infection. I was reading that wet food is good because it ups their water intake so I've been having her eat wet food in the morning and dry food at night. These are the questions I have:
1) Is there a good alternative all natural food for dogs that will help prevent urinary tract infections and bladder stones?
2) Can I continue to feed her Blue Buffalo or is Wellness or some other food better for her?
3) What is a really good wet food that isn't "junk" but is all natural that could help my baby up her water intake?
4) What can I do to prevent urinary tract infections and bladder stones?
Thanks,
Joanie