Does Pressero verify the print buyer's shipping address for FedEx or UPS?
Currently, the address entered by the print buyer is used as-is, it is not verified as correct. So, there is no shipping address verification.
Are Business vs. Residential rates supported?
UPS does apply Residential rates if that option is selected. There is no verification the address is residential.
There is a possibility of FedEx using Business vs. Residential. However there appears to be a bug in the FedEx API preventing this from working as intended and is being investigated with FedEx.