Hello Banksy, Darcy and Sunny - welcome to Purrs.
Sounds like you have your hands (and paws) well and truly full. Never mind. Once treated, fleas will usually disappear relatively quickly, and its great that you've had these little ones checked over. Well done.
I would treat the house though, as well as the cats, and I'd be asking the vet about using a spot on treatment for the kittens when they're old enough (usually at 12 weeks) - normally when treating kittens for fleas, you would have them wormed too, as fleas and worms often go together, I'm afraid.
For the house, I would use something like Acclaim, or Indorex. They're expensive, but are safe to use following the instructions (ie keeping the cats and other pets out of the rooms while spraying, leave to operate before re-admitting pets to the room). These products are lethal to fish, so make sure any fish tanks are suitably protected. Regular hoovering over the next two or three weeks will also help, making sure you hoover the cats bedding.
Washing pet bedding can kill off eggs and larvae if done at a high enough temperature, but sadly often ruin the pet bed at the same time, so hoovering and spraying are probably the best ways of dealing with those.
Bob Martin flea products are not worth using. Sadly, they can make your cats very sick, and there is a high incidence of death in cats where Bob Martin products have been used, so please steer clear of them. If you google cats, fleas and Bob Martin products you'll see what I mean.
Given you've inadvertently acquired a male and a female kitten, I would also ask your vet about having them neutered at around 4 months of age. Whilst this may sound young, cats can become sexually mature at an early age. We have one male cat and two females. The females were semi feral when we acquired them at around 8 weeks old. They came into their first season at just coming up to 5 months old.
So, how are you settling in with your new family members, apart from the fleas? What are they like and what colours are they? We love to hear about members furrkids.