You will need to log onto a wireless network somewhere at sometime to register your Kindle and activate some of the functionality.
You don't need WiFi to get books onto your Kindle though. As long as your Kindle is registered (see paragraph above), you can choose an option "Transfer via Computer" for purchasing and then you will be able to download to your computer via USB connection - simple drag-n-drop. However, you need to specify that you're downloading to add to your registered Kindle.
I'm guessing you could probably go to your nearest Maccas to use the free WiFi just to register the Kindle and then just shut off the WiFi and never think about it again.
Welcome, by the way.
Regards
Caleb