Recommendation on end-to-end SSL and certs

Dear SDN,

I am using an ep6 sp13 setup with

1 box in DMZ (web dispatcher and wgate for ITS)

1 portal CI behind firewall

1 portal DI behind firewall

I am looking to use a verisign cert on the DMZ box, so as to protect my ITS content,

Qestions are:

Can I get away with just using a cery for the web dispatcher? can I use end-to end ssl if I choose to use the same cert for my ITS?

Thanks

Jeremy