While I can't diagnose your Pommie's hair loss, nor the excess sheding. I will submit that brewers yeast can help with his coat and skin condition. The overweight thing concerns me, however. As animal lovers, we tend to love them too much, over-feeding, the wrong kind of treats, and such, will definitely lead to some real problems somewhere down the line.
As for your female, the exercise and the resulting weight loss, should be good for her. However, I submit, that proper nutrition, in tandum with the exercise, should be all that is required to maintain her good health.
I am a breeder of Pomeranians and I have had very good results with Purina's Puppy Chow, given to my adults as well as to my puppies. In addition to the Puppy Chow, I give my dogs a treat each night. I have found that chicken is a wonderful treat for your dog, especially the breast meat, cooked in the microwave. They receive the chicken as a healthy treat, not a meal, except on occasion. In conjuction with the foods, that my dogs receive, I make sure they get plenty of exercise, which counteracts the higher protien levels of their Puppy Chow. None of my dogs are overweight, I only have twenty. Should they show signs of weight gain, I just regulate their food intake. If you leave their food down in the "free choice" mode, some, not all, will tend to eat too much and gain weight. I feed mine a snack of Puppy Chow in the morning, then take the bowls up, and putting them back down late in the evening, just at our meal time. It works for me as they seem to be thriving and I have had no health problems thus far. I have been doing it this way for ten years. The only Pommie I have lost was due to a bad heart (from birth) and he was 12 years old.
I really think that exercise is the key in conjunction with their nutrition for the overall health of any dog, not just the Poms..