Do doctors prescribe patients zovifax for shingles, since shingles/chickenpox are cause by the herpes virus ?

Yes: Zovirax (acyclovir) can be used to treat shingles.

Depends on each case: Varicella-zoster virus (VZV) is one of eight herpes viruses known to cause human infection and is distributed worldwide, usually self limited but can cause significant complications, such as soft tissue infection, pneumonia, hepatitis, reye syndrome, and encephalitis. Patients at increased risk of complications include adults, pregnant women, and immunosuppressed hosts.