Hello Jim,
what do you understand under the term "standard table". Is it a SAP table or a table of a product for which you are not responsible for, than I would say do not alter it, to avoid any with e.g future SAP deliveries. An exception can be if you are using enhancement mechanisms for ERP tables on the NetWeaver stack, like Append structures.
If you are responsible for the tables in an AddOn or a product you can think about the enhancement of the original tables.
Regarding the second question you can check the Geocode functionality (Geocoding - SAP HANA Spatial Reference) delivered with the HANA spatial option. You have to convert your address data to geolocation information to be able to use it with the spatial functions.
Regards,
Florian