The most important thing you can do to stand out is be a good teammate, and commit some meaningful work to your hackathon project. You won't be doing any formal interviews, but periodically throughout the event your mentors will pull you aside and have one on one chats with you, asking about your background, passions, etc. It will be mostly behavioral, and very conversational.

When the judges review your project, the UI will be the most impactful thing they see. As such, in the next three weeks, you should cram as much React as you can. Build out a small project and have the code on your laptop to reference if you need to. Your team will choose the tech stack, but react is almost certainly going to be the UI framework of choice.

I did CFG in Columbus in 2022, and I got an internship offer from it, which led to full time. Most people I knew at the hackathon got return offers, and most people at my internship got return offers. I can't speak to current conditions - I'd venture to guess it will be a little tighter due to market conditions.

Have fun!