Is the form's appearance customisable?
Yes, by all means! There's a broad variety of options when it comes to developing a unique look for your form in order for it to stand out and catch the eye. Everything from the fonts to the color, slides, or the placement of every part. This shouldn't be an issue for people who are so invested in solving problems... with COMPUTERS! That's like a Spartan Race in which the average person would just wriggle around like a Magikarp.
And... although we don't think a hackathon is necessary to achieve the pretty, cool-looking design your event deserves, it's not up to us to decide so. The RAM is the limit!
Where can I post this form?
Again, lots of options, but mostly up to you. If you think most of the people who want to attend a hackathon follow your Facebook page, paste the link there. Maybe you have all their emails and prefer to do it that way? Also cool. If you are a fancy web owner, you might as well embed the form onto your platform to provide easy access. Or wait... you could actually hide the form somewhere in your web and turn it into some sort of cybernetic puzzle. Pretty epic way to make sure only the chosen ones arrive at their destination.
Is there a way to charge the registration fee price through the form?
If people have to pay in order to get into the event, there are easy ways for you to include that option inside the form. And that's pretty much it.