You KNEW this dog became pregnant in March, but you've done NO research up to this point?
And guess what - breed DOES matter, because certain toy breeds almost ALWAYS need a C-section. Do you really have at least $1,500 sitting around for just the procedure?
What do you mean "what we should be feeding her?" You feed her a high-quality, grain-free food - she needs the extra fat and protein right now. You should have been doing that this whole time, supplemented with the occasional raw meaty bone.
YES - she still needs walks outside. NO - you do NOT let her pee in the house, why would you??
What do you mean by "there are other dogs in the neighborhood and we wouldn't want to interfere"? What does that mean? She needs to be AWAY from all other dogs.
"....unless something goes wrong, and I doubt something will." What an attitude to take towards your poor dog! Are you financially prepared for complications? Are you even aware of the signs of an emergency?
Your b*tch should have been spayed as soon as you realize that she had mated. It's not as simple as sitting around and waiting for puppies. The fact that you think it IS that simple, makes me severely worried for your dog's welfare. Please get her the veterinary assistance that she requires, and relinquish her to a no-kill shelter as soon as possible. The fact that you willfully CHOOSE to remain ignorant, instead of learning all you can from other GOOD breeders and veterinary professionals, just blows my mind. Your b*tch could easily DIE due to your ignorance.
EDIT: Ahhh . . . . so you're deliberately breeding untested, untitled mutts. I see. You need to surrender your dog immediately to a no-kill rescue so that she can receive the medical attention she desperately needs, and you need to not own any more dogs, ever again.
If you cannot use the brain God gave you and refrain from creating more genetically sick mixed breeds, when we ALREADY have literally HUNDREDS of THOUSANDS of them in shelters and pounds, dying every day, then no, you are not ready for the responsibility of owning a dog.