Well for a .COM.AU you have to have either an ABN or a business name registered (a number will be generated and used for reference).

.COM there are no rules, so you can get it.  I would advise private registration on a .com (reduces spam) and you don't want your address being shown on the lookups as there are some nutters in this hobby.   

A whole new lot of TLD's are being released soon, like .GURU and others.

You can purchase other overseas TLD domains such as .TW (Taiwan), .CO (Columbia) but IMHO its not very professional to be operating a domain for an online presence when your not in that country or operating from that country.

A .ORG and .ORG.AU are ONLY for not for profit arrangements and this is enforced.

No issues with a swinks-pinball.com (ie hyphen), but if the one that is already registered (ie the .COM) is a similar business then I probably wouldn't.

Gone are the days where you would go to http://www.redumbrellasforelephants.com when you're looking for a red umbrella for an elephant.  SEO (Search Engine Optimization) is the key and getting a good ranking on the google machine is of a higher priority than a domain name.