I need some public speaking tips

Okay. Soooooo....
I wrote an article (several actually, through the years) in my professional trade magazine. It came out this month. I'm getting emails and texts from folks telling me how much they loved the article. My profession is court reporting - the stenographer who is at the front of the courtroom typing everything up.
I have now been asked to come speak at a court reporting convention this summer. I've never done any public speaking, much less at a convention with a bunch of people in my profession who may know even more than I do on the subject.
I would like some advice from folks who have done professional speaking before.

1. Do I ask for a fee to speak? If so, how much?
2. Should I expect them to cover my expenses to and from the convention - flying out there, hotel, etc?
3. Any tips on how to make folks laugh and be relaxed during my presentation? I want to make the subject matter be entertaining to an extent.

Thanks in advance.
Tari