Don't overcomplicate it

Maybe you could require some Zoology knowledge to act appropriately, but the spell mentions no need for it. So just assume that you know what each body part is used for in which circumstance but use the appropriate skills of the character.
If you cast it on an unarmed specialist then he will do fine as a tiger, but casting it on Joe Couchpotatoe wouldn't do much.
It doesn't mention that you get the skills, so you don't.
It doesn't mention that you need specific knowledge, so you don't.
For how to use tests refer to the specific chapters, nothing changes about that.