Count me in!
In response to the dash & net question - does it make it harder to rank - I'd say an emphatic NO! - it doesn't impact ranking except perhaps indirectly as follows:
One of the factors that Google use for their ranking formula is CTR (click through rate) weighted as to the position in the search results. So if result number 2 gets more clicks than result number 1, that would, over time, help result number 2 leapfrog result number 1. Of course there are many other factors so it might never happen.
Human nature may dictate that people are less likely to click on a hyphenated net.au than a 'normal' com.au so this might negatively inpact the CTR and therefore and a secondary effect the ranking.
Rhythm, in answer to your Q's
1) As DMP said it does have some backlinks.... but not that many considering. I guess that's what's exciting about it from a domain POV
2) Search Traffic is 89%, Type-in 3, Referring sites 8%
3) We paid a professional to write the content so it didn't take long at all. Cost a few hundred through...
4) I think it's only recently hit the number 1 spot for 'debit card' so 3 months or so. However it was showing up on the first page from the 1st week.
In terms of the comp - I reckon the organiser thinks of a bizzare search term "red violin mixer" and assigns participants a domain name each
redviolinmixer.com.au
redviolinmixer.net.au
red-violin-mixer.com.au
red-violin-mixer.net.au
Then each participant develops & SEO's a site to see who has the best ranking for that term in 2 months time, say. It won't prove whether extensions make a difference but it would be a bit of fun for the SEO side.