Well, the first time we saw a Dusk imitating Vivi (At the Struggle tournament), it just giggled and said Roxas' name (Albeit with odd pauses).
However, laterl, another Dusk imitated Vivi flawlessly (In the tunnel).
That could suggest that there are different levels of intelligence even among the Dusk. Maybe some are capable of more advanced thinking? It could be that some people's hearts weren't quite strong enough to produce a Nobody of a higher rank than a Dusk, but were still greater than the majority of the "Lesser Nobodies".
There may be forms, but I doubt there will be Drive Forms.
Judging from the previews, you have no companions (Donald, Goofy, etc.). And the three main characters are supposed to be separated throughout the game. So Drive Forms seem to be impossible...
