Advice for my first paid gig

Hello r/filmmakers, need some advice on how much I should charge and what I will need. I originally posted this on /r/ videography but I couldn't get a response so I hope its ok to post here.

A little background: I am 16 years old, and this will be my first paid video gig, aside from a paid photo shoot I did for an acquaintance. I have 3 projects in my reel, but they are all no budget. I volunteer at a program (run by my friend) at the local library, and the librarians were impressed at the promotional video I created for said program, and asked to hire me to shoot a ted talk style video for an event. This event is 2 hours long, and they want b-roll of the audience mixed in when I edit. The organizer seems to know a bit about video production since she asked about my editing software and my lens.

What are some questions I should ask? Will I need a second shooter? How much money should I charge?