I think this is a brilliant idea, if I only lived closer to Berlin I would definitely be interested in joining this group!
Editing on a Mac computer does not instantly make you a 'professional' editor, neither does editing on a Windows computer.
I always edit on Mac computers myself, mainly because from my own experiences Mac computers have a lot less crashes and errors while editing in comparising with Windows computers. So even though Mac's are heavily overpriced, and does not instantly make you a 'professional', I agree with Raph Dae 'once you go Mac, you never go back.'.
I'm a film student from the Netherlands, and I really do like the idea of your upcoming short, so I surely want to help you out!
personally I always use Adobe Encore to burn my video's to DVD. It's very easy to use, and I have never experienced any quality loss. One YouTube tutorial is probably enough for you to understand the software, so maybe you could try that out. I must say I'm not an expert on burning DVD's, but at least this is how I do it.