Hi Princess. Yes, you are full of questions. But you're asking things that lots of other people may be afraid to ask--so keep 'em coming.
Finding a foster mom with four feet is always preferable to we clumsy bipedal creatures. Kittens raised by a queen are better adjusted, and I believe healthier, than one that you or I can nurse. After all, they can eat on demand. Mom keeps them squeaky clean. She can talk to them in their own language. She keeps them just the right temperature. And she and the siblings will teach the kitten everything he needs to know to be a happy, well adjusted cat, like don't bite, keep your claws sheathed when you play and use your litter box.
If the queen is alive, but unable to nurse (maybe she has mastitis), let her do her other motherly duties and you can feed them. If she has a virus or something contagious, you might need to remove them entirely. But not necessarily. Last year I had a mom with a cold. The vet prescribed Clavamox and told me to remove the kittens and hand feed them because the antibiotics Clavamox would hurt the babies. I discussed it with a breeder who recommended I leave the kittens with mom. She said they would receive a reduced dose of antibiotics through the milk. After all, they'd already been exposed. Everyone was fine.
If you can find a mamma cat, the kittens should be close to the same age, otherwise the older kittens could hurt the younger ones or keep them from getting dinner.
Most mom cats readily accept orphans close to their kittens age even without a lot of deception. But it never hurts to be safe. Take a towel or wash cloth and hold one of her original kittens in it for a few minutes. Then wrap it around the orphan(s). They start to smell like her own baby. If she hisses or you are still concerned, place a drop of little vanilla on top of the orphan's tail at the base (not on his little anus.) Do the same thing to her own kittens. This masks everyone's scent.
When you put the new kitten in with the litter, stand back and watch. Most of the time mom will start licking just as she would her own baby. Don't leave the kitten alone until you are confident mom has accepted her new position. It's a rare queen that won't accept a kitten but it does happen. If you aren't comfortable with her, then get the bottles out. You need to prepare the formula.