Wow..
It sounds like you have a lot of problems with those kitties. However I think its all related to the same thing !! Dry air, seasonal changes in the environment. People all react in different ways as well, we get dry cracked noses, itchy elbows and knees, watery eyes, running itchy ears. Lets not panic too much. One old fashioned remedy for dry skin problems in cats it Cod Liver Oil. Cats love it, its fishy and smelly but does wonders for them. not just the skin, but degestive tract, hairballs, dry coughs etc... Try keeping the Humidity in the house up around 60%. it may take more than one of the small table top units to achieve this, but its still alot cheaper than visits to the vet. If the cat with the very itchy skin, I'd try some childrens moisturizing shampoo & conditioner, its mild and won't unset the tummy from licking. Also try giving them a little moist / canned food daily, as long as they still eat the dry thats good for teeth its not going to hurt in the short term..... I have 9 babies, all have some minor problems since the weather got cold and dryer, and all have responded nicely to the added cod liver oil and humidifers.... Hope this makes sense and hope it helps you out...