Yes they are. In my training level dressage test, I kissed to asked for canter and the judge docked me on it. However, I would rather forfeit a few points to a kiss than lose a lot to a crappy transition. We were also only in a training level, so it wasn't that big of a deal.
Yes, I've lost points this weekend because I talked to my horse :(
Yes it is! Voice and click are totally forbidden in a dressage test :)