Try having a litter of 15 that need their nails doing

I used to do mine when they were really sleepy, either leaving them where they were and doing their nails whilst they were asleep, or getting a helper to gently hold them while I did the nails. You might find that weekly is not quite enough - I don't know about your breed, but mine seemed to need doing more often.
I usually start weaning at about 3 weeks. I meal on the first day, 2 on the second, up to 5 meals a day by 4 weeks. As to amount, I am guided by how much they eat. If it all goes, I put a bit more down next time. I like to have a little bit left over after a meal, then you know that all the pups have had their chance to eat as much as they want. And remember to have water available all the time now you are giving them complete food.
PS I'd remove the breed if I were you - it's against TOS to name your breed of puppy, but you could give a guide as to the adult's size.
Best wishes with your babies
Carina