Hi again, Emma and you're most welcome!
Thanks very much for your reply with additional information.
It does sound like the kittens are thriving and that's great news! She is an excellent momma and in answer to your question, yes, when she 'cleans' them with her rough tongue, she stimulates them to eliminate and she does ingest the urine and feces as they come out.
The sound you're hearing, 'may' be a tiny sneeze, but as long as you seen no symptoms of a URI and they continue to nurse and seem content, everything should be fine. Yes, having a vet come to you is more expensive than an office visit, and as long as their thriving and showing no symptoms of illness, you can wait until they're 6 weeks to bring them in, unless you notice any unusual symptoms before then.
I think you may have misunderstood what I said in my previous answer, as I was saying it's important that the nursing MOM cat eats a diet of kitten food, as it contains extra calories and is richer with nutrition, which she needs since she's nursing. However, if she is doing well on her usual diet and eating more than adequately, that should be fine. It's way to early to introduce the kittens to 'solid' (canned) kitten food just yet. That is usually done at about 4-5 weeks of age, although the kittens should still be nursing until about 8 weeks of age. They should not be removed from the mom cat until 12 weeks of age, as that will give them enough time to learn good habits (like litterbox training) and socialization skills from their mom and siblings before they go to their new homes. I'm so glad you already have new homes lined up for them!
The fact that you are able to hold and pet the kittens and the momma now trusts you is fantastic! The earlier kittens are socialized by humans, the better, as they will adapt better to their new homes.
I'm so glad you've decided to keep 2 of the babies!
Yes, I know nurses work long hours, but it is a wonderful 'helping' profession and bless you for undertaking it! My sister is a nurse here in the US and coincidentally, my friend in Birmingham, UK, is also a nurse!
It's my pleasure to be of help to you and your new feline family and please let me know if you have any other concerns or questions.
Positive feedback would be greatly appreciated and once you rate my answer, please don't worry that we will no longer be able to communicate, because you can click "Reply" at any time and I will always be here to answer any follow up questions you may have.
Keep doing what you're doing--everything is going fine!