although your question is out of scope of this forum i will try to help you.
I would like to be able to print from the server to a local printer attached to the OpenVPN client. As I understand it, I need to add this printer to the CUPS interface on the OpenVPN server.
1. Is this assumption correct?
yeap
Do I add the printer with a URI something like (vpn IP of client) 10.x.x.x./printers/hplaserjet?
you probably need vpns client ip to redirect the print there,but you need to select which protocol
you will use for printing (f.e lpd or cifs)
what other steps are needed?
if you have ip connectivity then its purely printing service setup,
your client what OS has?
Michael.