Does the whirlwind thingy not respond to my diplomacy attempt, or at least to my words?
It normally takes 1 minute to make a diplomacy check. If you rush it (or bind naberius, or whatever...) you can do it as a standard action. Rushing gives you a -10 penalty. So assuming you're rushing, no there is no response. If you're not rushing... well... you'll have to stand there and hope he listens to you for 10 rounds.
Interestingly enough, Intimidate when used as pseudo-diplomacy (as Xuuvosic did with the barghest) actually works a lot better for diplomacy, because you can do it as a standard action. It doesn't last as long, though. You can intimidate someone to back down from fighting you a lot better than you can talk them out of it diplomatically, which I guess makes a certain amount of sense...
Diplomacy should come in handy for other parts of the campaign, but unless you're a binder or something it generally isn't going to talk you out of impending or active combat.
If you offered some kind of fantastic deal, though, that would counter the -10 for hurrying. From the Diplomacy rules I'm using:
-10 Fantastic: The reward for accepting the deal is very worthwhile, and the risk is either acceptable or extremely unlikely. The best-case scenario is a virtual guarantee. Example: An offer to pay a lot of gold for something of no value to the subject, such as information that is not a secret.