Hi Pathfinder.
I have a friend in the Navy, who often works with both the the US Navy and Army, and he says the same thing about you guys! I guess there is a mutual respect
As for your questions:
Yes, you can buy land. However, each state has different laws regarding running a business. I suspect you may have problems getting a business license. You may need to become an Australian citizen.
You can find info at
http://www.immi.gov.au/ maybe email them with your questions.
As was stated, goto
http://www.realestate.com.au and look under rural for an idea of prices. The conversion to US$ is made by multiplying the AUS price by 0.55
Good Luck with it.