A Fluffy Kitty Cat

Okay so, my mom is considering letting me get a cat, but she's a bit wary. Please, help me convince her that it's a good idea!

Little bit about our home:

-We live in a suburban area
-We have a small, fenced in back yard
-We have two dogs and two guinea pigs who I keep in my bedroom with the door closed at all times

Why we want the cat:

-We have a major vole issue in our back yard that we're hoping the cat can help solve
-I want another fluffy animal <3

Things we're worried about:
-My mom is allergic to cat pee, will this be solved if we get a she cat?
-Whether or not the cat and our dogs will tolerate each other. If we get a kitten, could they adjust?
-Furniture. We don't want the cat ruining our couches. We can't declaw her if she's going to catch voles.


Thanks for your help in advance!

1. get a covered litterbox and if you're getting a kitten train him/her fast
2. get toys and a scratching post and other places to sleep, if your cat still ruins the furniture maybe that cat doesn't understand or is destructive
3. Leash the dog and cat (or hold the cat) so they can get used to eachother from a safe distance
4. also sweet dogs to humans can also be to cats, once my cat broke his leg and my dog tried to warn us, so sweet.
5. Since you live in a large area, if there are friendly cats around (and your cats is friendly too) let him explore so he wont be lonely when your gone for the night (my cat meows at my door when i'm sleeping over at a friend's or family's house) or week, Etc.
6. a kitten might be scared but i think most friendly dogs are either afraid of their tiny bodies for a bit or are really gentle to kittens

Thank you for the advice!

I'm still a bit worried about our dogs, they are both medium sized and rather aggressive. It takes them a while to get used to other dogs, so we have to be very careful when taking them on walks. A smaller dog once got into our backyard through a hole, and our dogs bit the poor thing's paw. I'm not sure if it was broken or not, but I know that it did have to go to the vet. I'm afraid they'll display the same behavior to a cat. Nora, my 3 year old female, is very timid, and will snarl and bite at things she doesn't like or trust. Gizmo, my 2 year old male, is VERY hyper and intelligent. He loves to rough house, and has a bad habit of jumping on people and playfully biting hands. Neither have ever injured a human past a scratch or two. They are very friendly towards humans, it's only other dogs they have issues with. My grandpa also has a dog, who they see often. Nora growls at her for a good 10-15 minutes when we get there before she calms down. She has never bitten her. Both Nora and Gizmo seem to be less aggressive towards dogs who are not aggressive in return, especially if they're not on their own home territory. They have never interacted with a cat.