Both Wi-Fi only and cellular iPad Air/Mini/Pro models are compatible. Only cellular models have GPS. You do not have to activate the cell service in order to use the GPS. The DJI GO app currently only requires GPS on an Apple device when using the Follow Me feature or to reset the home point to your current location if you've moved elsewhere after taking off. If you're going to use a Wi-Fi only Apple device, you could attach a Bluetooth GPS receiver (like one of these) to add GPS later if needed.
Must be a member from Santa Cruz , Ca . Welcome to the forums!
Now get out there pickup a new device and capture some epic Santa Cruz moments. Upload them to YouTube and link here in the Photos and Videos section. Man I miss seeing Santa Cruz in the morning riding my mountain bike!