Double Post gets same answer:
If you were out with friends a third time and he was there would he try again? More than likely.
First time he got a kiss from you, second time it went progressively further, third time well in his mind this will be the one to close the deal.
If you dont bang him by then, dont expect to hear from him as you will then be labeled a cock tease.
As for exclusivity could be something you discuss before or after, as a guy I would hope she brings it up after.
If your into him go for it, bang him, and afterwards tell him if he commits to only having sex with you he could have it "X" where "X" is how often you want it.
Although know that once you do bang him you will become emotionally attached and fall in love with him.
Maybe there's no peace in this world, for us or for anyone else, I do not know. But I do know that, as long as we live, we must remain true to ourselves.