At one stage hyphenated domains were thought to be more seo friendly, but thats not the case any more. I would go for the non hyphenated version if possible because its easier to type in. Most traffic will come from links though, so its only a small gain (unless you become a real brand).
As far as .org or .net, it probably doesn’t really matter unless you are concerned about branding and having people type in your domain. In that case a .com is preferable, since its the choice most people try first when finding a companies web site.. If you have lots of seo friendly content the search engines couldn’t care what tld you have. For the sake of branding i personally prefer .net over .org.
When you choose your .net or .org site, be carefull that the .com version is not already established and a running concern, since you may be headed for trouble. Often the .com version will just be parked somewhere, so its more than likely ok to snap up the .net or .org and launch your site.