When the ipad is synced and i mean synced as in "iphone hotspot" it allows the wifi only ipad to use the iphones gps functionality and then i dont need to go buy a external receiver. I didnt buy the 3G model tablet, because i only use it at University and wifi is plentiful. But if you do have the 3G model then you're correct, no cellular data connection is needed. Syncing the phone allows me to get around the wifi only problem. The sync also allows any iMessages and emails can pop up on my ipad, instead of pulling out my phone to see the message.
Basically just working with the tools i have haha