Congratulations on your upcoming litter! We would love for you to keep us posted on her pregnancy and if you have any further questions there is always someone her willing to give an answer. You may want to post them in the breeders section though, the nursery is normally a place to show those puppy pictures after they are born.
My advice would be to feed her a high quality puppy food from now until her pups are weaned and allow her to eat as much as she wants. This early, she may go off her food from time to time with her tummy adjusting to being pregnant, but in a couple of weeks her appetite will increase. Do not supplement her with calcium during pregnancy, wait until AFTER the pups are whelped. Feeding additional calcium during pregnancy can fool her body into thinking it does not have to produce it on its own, possibly causing problems with eclampsia later on. My vet tells me feeding her a high quality puppy food will give her all the added nutrients she should need during pregnancy.