Is GPS free?

Turn on Location only when needed. Turn off Location History. Some would say set to GPS Only.
 
Yes, the technology is free to use, but some software, for example navigation software like Sygic, may be paid. Google Maps is free, though :)
 
It is free to use the App but it does suck data from your plan.
To be clear GPS doesn't use data, but the app using GPS (like maps) may use data to load new areas as you travel.

As already pointed out, Google Maps will let you store some data so you won't have to get it while moving about.

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Should there be smoke coming out of my cpu?