Yes, Go will connect as long as you can communicate to the FileMaker Server. It does not matter if it is cell or WIFI. Lot's of people even use WIFI only iPad's and just connect them to their Hot Spot's on their iPhones for Data..
There are some extra steps in setting this up to work from an outside network. You will have to setup port forwarding and open the port on your firewall. For example you want to connect to your server from your client's office. There are several user on this forum will to help with the information you need to set that up when you get to that point. There are not any difference in connecting with cell or WIFI except speed and price. Wifi is usually faster and cheaper.
Tanks, Stacy! I deployed my FileMaker Server yesterday and tested it from an outside network with an iPhone 6 and with FM Pro. I'm still having issues with the SSL certificate, but that appears to only affect WebDirect users.