This is a question for a veterinarian, sometimes they will recommend advantage (off label use), bathing with gentle soap, and treat the adult cats with advantage.
Just let your cat have her babies....
This varies by breed but with any breed the litters will start to get smaller as the cat becomes older.
Vinegar
No, it is not possible for a spayed cat to have kittens. The spaying procedure removes the cat's entire reproductive system, which includes any unborn kittens if any are present. If the cat is far into her pregnancy, it may be safer (unless a vet says otherwise) to let the kittens be born and then spay the mother as soon as the kittens are weaned. A cat early in pregnancy can be spayed safely.
It is important to read the labels because it contains vital information on how to use the product safely and effectively.
A golf club
Countertop grills can be a safe product to operate as long as the operator knows the product and knows how to use the product correctly, reading the manual and doing some research on the product is the best way to know you are using the product correctly and safely.
yes
Safely around 100
Yes they do. Sometimes these sacs bursts while the kitten is in the birth canal, sometimes they don't. The mother cat should make sure the kitten is safely out of the sac once it is born, if she does not you should do this, if not, the kitten will not be able to breathe! If the sac bursts before the kitten is born, the mother should pass it soon. Sometimes female cats eat the placenta, don't be alarmed if you do not find any, this is what is likely to have happened.
None. Any product to get rid of rust will seriously harm or kill birds. It's best just to replace the bird bath.
That would depend on the drug used, but it's typically not recommended to deworm kittens until about 3 weeks of age due to the lifecycle of the parasites that should be targetted in a kitten that young (roundworms) and the drugs that can be safely used in kittens. There are of course other parasites that can cause issues in kittens under 3 weeks of age, but you cannot purchase over-the-counter medications for them nor can you diagnose them simply by looking at feces for worms.