I wouldn't worry to much about the patchy or thin fur, unless someone can give you a good reason to. some days ours seem to have ugly fur, then the next night they look alot better.
for me the yellow is hard to say. some say diet, but OHPW is a good diet, so is BML. If your gliders are new and still scared one may pee in pouch, leading to some yellow. but if they are yellow slightly it will take time to work out.
keep reading and learning, lots of myths and overblown issues out there. If you have a good vet, save up some questions for them.
Also some good glider books available, I had an animal planet one that was great, informative and balanced but gave it away.