weretigers (This one made no sense to me, what do you call a Khajitt weretiger? How do you tell when they changed?)...
You call them a weretiger just like everyone else. Werelions (lions, not tigers, dunno where you got tiger from) are actually native to Elsweyr, so it's not really that odd of a concept.
It really seemed like someone in the Lore department of Beth, decided to start throwing 'were' before any random animal on their kids Alphabet trainer.
That's actually a valid way of doing it. The word werewolf is composed of two words: "were" which means man and "wolf" which means, well, wolf. Earth has stories of more than just wolf transformations. I've heard of bears, cats, hyenas, dolphins, coyotes, ravens, rats...every culture has at least one in their legends.