I need some advice about which kitty litter is best to use. And how to get pet stains out of the carpet and how to keep the smells out of the house. I would also like to know, how often should you bath a ferret? I've heard some people say every week, some say every month and some say every other month.

I don't own a ferret or a cat, but maybe some of what I know about dogs will help. I don't know how to train cats and ferrets, but this paragraph from my dog material may help keep you house fresh.

Clean up accidents promptly. I mostly keep the little
Puppies out of the carpeted rooms. Still I need the can of carpet foam
Sometimes. First blot up all the urine you can with a dry towel. Keep moving
It and stepping on it until a fresh area stays dry. A couple big putty knives
Work well on bowel movements. Just slide one under it while holding it with
The other. This gets it up with a minimum of pushing it down into the carpet.
This works with even relatively soft ones, vomit, dirt from over turned house
Plants, or anything else from solids to thick liquids. Finish up with a good
Shot of carpet foam. Note, do not let the puppy lick up the carpet foam.
Once the dog is reliably housebroken, your carpet may need a good steam cleaning.

I know that bathing dogs too often often leads to skin problems. With dogs, you can almost eliminate baths by brushing frequently and limiting what they are allowed to roll in. Swims in decent water help too. My 11 year old Aster swims in the river weekly, but hasn't had a bath since coming to live with us over a year ago.