I usually go like this:
Go to the front and say hello, then give them your resume and say: I want to apply for that position;
Recruiters usually have a brief look at your resume, and if he is interested in you, he will ask you some questions.
Finally, they usually tell you a deadline, that is, the latest time to inform you of the interview.
Technical and salary issues will be discussed during the interview, but generally not at the job fair.