I agree . . but seriously who could resist that array of delights you are feeding him.
No wonder he is gaining rapidly. Once you get these little ones in the habit of eating a secondary food source its hard to get them to eat any dry kibble but not impossible. Have you tried mixing his wet food and cooked foods in with the kibble?
The weight gain seems normal for a pup that age. Typically anywhere from 2-6 oz per week in the norm. They will continue to grow until they are about 15-18 months of age and than unless they are being overfed they will retain that weight to be the average.
Hypoglycemia is caused by stress and lack of food and the proper amount of rest. As long as your pup is getting plenty of rest and three square meals per day he should do ok. Its important that he isn't overexerted and if he does that is when you would use the nutra cal. I'm not sure its such a good idea to be so dependent on it. He should be getting his strength form proper nutritional meals. I have only ever given Nutri cal if I suspect a pup is in need of a pick me up after playing and are possibly having a low sugar attack.