a) Geocoder only charges for their data if you need it without the restrictions of the ODbLicence it's released under (basically attribution, share-alike). b)

a) Geocoder only charges for their data if you need it without the restrictions of the ODbLicence it's released under (basically attribution, share-alike). b) giving it away for free would not actually change anything legally. You can still get sued for copyright infringement even if you don't make any money on it.