ZlatasPop, at the risk of hijacking this thread for a moment here - but the fact that you paid $2000 for your dog isn't of any importance at all. genetic disasters from puppy mills are sold for the same amount or more to people who don't know or care enough to investigate where to buy from, and it is possible to get a good quality dog from a responsible breeder for less than that. i've heard people paid $3500 for pet store dobes that later on didn't even conform to the breed standard and i have a friend who paid $800 for a show quality dobe because she couldn't afford more and the breeder wanted the pup to go to a good working/show home.
i know you're a first time owner, so you probably aren't aware of this, but "inexpensive mutt" is a fairly offensive term to many people who might not own "perfect" show quality specimens or not even purebred dogs. that kind of terminology is totally out of place on a forum like this where dog lovers of all kinds hang out.
how much you pay doesn't make your dog. it's what you put into it that counts. and unless you absolutely want a conformation title on a dog, it doesn't matter if it's purebred or not.
now, back to the supplements.
vitamin C has many benefits, and a lack of it in the diet can lead to many problems. however, regardless of that you need to be aware that until the puppy has completed teething the ear cartilage will remain floppy and there is no guarantee the ears will stand up perfectly straight. sometimes it's even just the tips that flop over and need to be supported.
do absolutely not give a growing puppy (especially large breed) any calcium supplement, that's just inviting disaster since it can lead to all kinds of orthopedic problems.
feeding 2 eggs and half a cup of cottage cheese actually supplies more phosphorus than calcium, which means that the body has to draw extra calcium from somewhere else in order to achieve balance, so i question the usefulness.
that's not to say that raw eggs and cottage cheese don't make good additions to a feeding regimen (especially if you only feed commercial food otherwise), but you need to be aware of just what exactly you are feeding and how it affects the diet overall.