The form was asking if you knew how to do those things, not saying "you better know how to do this or else!". A little preparation in those areas may be nice, but judging from the situation, you don't need to spend all your time coding.
Here's my thoughts on it: if you're going to do an "experience and learn" type thing, you want to be in a position to get the most out of it, right? For example, I'm in an engineering internship right now (I'm a little younger than you, and my situation is kind of odd, but what I'm doing is pretty similar to what you'll be doing, sounds like).
If I didn't know some math and programming, and some bare basics about electronics, it'd be pretty miserable for everyone involved. But nobody expects me to win a Noble Prize in my first week. Everyone expects that, hey, I'm learning, and I'm probably going to need guidance to solve a problem, and I might need instruction in how to use such and such program, or whatever.
So what I'd do if I were you: brush up on programming, trying to understand the basics. You don't know what language they're using, and you have some Java/C syntax experience, so maybe try a different, easier language like Python that's quicker to write (or do whatever language you're most comfortable with; I just happen to be a Python fan) and try solving some of the Euler problems online (not problems written by Euler; they're just called that) using programs you write. That's a good way to practice if you know what you're doing to some extent, but need practice.
(Don't be afraid to google "finding length of list in [language]" or "doing [thingamajig] in [language]". I feel like, especially when starting out, a lot of programming means: run into problem, google error, google function used to solve error, type into program and adjust for situation.)
You can also review math (algebra II should be sufficient; I assume you've already taken it) and a little of the physics you've done if you want. If you've ever used a CAD program, you can review using that; if you haven't, maybe try downloading Autodesk Inventor - it's free for the non-pro edition, or something like that - and go through some tutorials with it so you get an idea how to use it.
Maybe look up some stuff about electronics, or about circuit board layout programs (I think there's one called Autodesk Eagle that might be free like Inventor). I don't know what all your thing will cover, but you get the idea. If you think something'll be covered, try to get a cursory knowledge of that thing, so you know what questions to ask and you're confident in your ability to, at the very minimum, figure things out going into it.
In the end, it sounds like you're going to learn a lot. "The forum sounds intimidating." That means there's a lot of cool people and topics that you don't know about yet that you're going to learn about! That's pretty cool.
Also, feel free to ping me in chat or in the comments if you want any specific advice on resources for different things.