[Whewt22]

"I believe that he is a menos adjuchas due to his unique abilities, the lowest form of hollow we've ever really seen to have those types"

Many normal hollow have unique abilities... Rewatch some of the earlier episodes, take for example;
Shrieker - the hollow that could create bombs attach them to you, and explode them with the pitch of his tounge.
Or the hollow that Orihime first fought, that could take control of a certain body part.

Grand was most likely just a Gillian, and made into an incomplete arrancar, ie. his size.

But you still can't get me to believe Ulquiorra looks human. Take a moment and compare him with our known top 3 espada. Them looking more human isnt strange, since the more intelligence they have the more human they look. Or it could be due to the fact the the top three are Vastros, and this is supported by the 3 ex-espada.