Custom fields of the table order are for asking data to the user, not to get automatically information on him.
The group id of the user is know. There is no need to collect it. When you're looking at an order, you can access the user page in HikaShop via an icon next to the username. From there, you can access the joomla user options which will give you the group of the user.
For the geolocation, there is actually a geolocation plugin which does that and which needs to be configured and published:
www.hikashop.com/en/support/documentatio...hop-geolocation.html
There is no need for custom fields or for coding for what you want.