As far as i know, there were males in every trailer. as for "Him", i do not think he appeared. but as for "him", maybe, considering theres about 6-7 billion people who can be referred to like that.
Crabcat was in Pacific Rim: Training Day; a fan film supported by the production behind Pacific Rim.
Since they were allowed to use the music from the film, a character from the film, and the film's director, couldn't it be said that this is canon, or at least a humerous footnote to the larger narrative? Could serious versions of the mechs/characters ever appear in future PR media?
Not really, no. I think "Lt. Commander" was just "Lt. Commander"; he just happened to look like Chuck by virtue of his actor. If they did, I'd be surprised, but I doubt Crabcat is going to be canon at any point.
It seems pretty unlikely that this will go farther than it has, that ebing farther than outside the promotional video.