You can geotarget by country, state, city, radius or zipcode. But to save time, GeoTargeting Pro lets you create custom regions that include unlimited locations. You can then target all those locations just by adding a rule for your region.
No! You can use all of Geotargeting Pro's features without needing any special knowledge. The PHP API is there for developers if they want it, but you don't need to use it to benefit from Geotargeting Pro.