the main point is that Stormy seas forces you to a particular action that can be in conflict with the declared one, while Escape as a bat should allow you to move in the same city you previously have pointed out as your next move. Not to mention that Dracula is not obliged to play the Escape as a bat, he can make the combat end even in different ways.
Stormy Seas doesn't really force an action, except Dracula's if he happens to be in the named sea zone. It can't be played on a sea zone that contains a hunter. Nor is the Hunter ever going to be obliged to play Stormy Seas in such a way as to invalidate his or another hunter's declared move. Even if he really wants to play the card, there are plenty of sea zones to choose from, he doesn't need to pick the one he or his friend are going to be moving into next turn.
I'm not saying your interpretation is wrong, mind you. To be honest I think both ideas have merit within the rules and nothing to show them incorrect. It mostly comes down to a gut reaction which one you should use in your own games. My point is just that the hunter has a certain level of choice with Stormy Seas, but apparently there's an expectation that he could do this to himself anyway.
Don't know. Hypnosis seems to be very dogmatic on the "next move" thing. I'd say that if Dracula moves in a different way because he plays, by his own will, a particular card, well, it's more like he's cheating. Just a personal point of view, obviously (and something that I'm not so happy to say, since I've almost always played Dracula)
I think any game mechanic that attempts to fix events which haven't happened yet is going to be fraught with such ambiguities. I also agree with the idea that this sort of card play is akin to cheating. If the window is open in the rules, however, there may be times when losing a turn is preferable to carrying out a predetermined action that is against your favour. It's not like you don't get punished for manipulating yourself out of your declared action.
The more I think about though, the more I wonder: The idea behind declared actions is that the opposing player will know where you are at the end of your next movement phase (this is particularly important in the case of the hunters getting a declared move out of Dracula.) If Dracula's play of Escape as Bat ends up counting as his declared move and forces him to go where he said he would, then he is free on his own turn to move on to another place. He will no longer be in the declared position he was expected to be. By my interpretation of the Escape it is still possible for him to be elsewhere, of course, but at least he loses a turn in that place for his efforts.
I suppose we could always ask FFG for a clarification if we wanted an absolute ruling, although I'm personally inclined to just leave it as "do whichever feels right to you and your group."