Ok guys update time! So I took him to this great vet today, who first of all told me he did look like a Yorkie, and could probably just be either a big Yorkie, or a a Yorkie mixed with another terrier. He said the long legs weren't uncommon.
The dandruff? Apparently he had ticks as a puppy and they gave the poor guy a treatment that made his skin too dry
so he gave him a shot for that, and will send him some tablets. And after that, a special shampoo
He said he looks perfectly healthy, and that we'll just have to wait a while to see if he stays this way or develops any other distinctive characteristics, but as far as he can tell, he's a Yorkie.
He also did the ear taping thing some of you mentioned, and he was so calm while they were doing it! He's a little angel.