DH and I are both residents of Illinois. IL has a clause that military members and their families can drive, legally, on their expired license for 6 months following either returning to the state, or leaving the military. It was somethingi had to apply for, and I received a card to carry with my license. You need to look into the laws in your state of residency.
As far as registration goes, do it by mail/Internet. Some states require emissions or state inspections to renew plates. Most states have agreements with other states to accept their inspections/emissions tests if they are required to renew. In which case, you get the required tests done in your current state, fax the paperwork, and renew your registration.