Hey,
Are these just 7 diverse customer sites which want to connect to each other via Layer3 VPN? The interface from your customer edge router to the provider edge router will depend on the means used to interconnect (fibre / ethernet / serial etc), The physical interface doesn't matter, the CE routers won't need to know MPLS. They will however need a static route to the service provider or you will need to implement a dynamic routing protocol (rip2, ospf, eigrp, ebgp from memory if cisco) - thats something you to have to agree on with whoevers providing the service. Addressing concerns for your host and linking subnets should be at your disgression because your SP will use a unique route distinguisher to seperate multiple incoming private addresses from different routing instances (you obviously can't have overlaps in your private addressing though).
