I should stay out of this, Larry... But... I can't help it...
I went to google and typed in RC turbine waiver AMA
and got a lot of info.
Seems the most recently dated document regarding this subject is this one, effective July 26, 2008.http://www.modelaircraft.org/PDF-files/510-A.pdf
Here are a couple of excepts from that document:
"An AMA member may be permitted to fly a turbine powered model on the slave transmitter of a buddy box as long as the master transmitter is operated by an experienced waiver affidavit holder. All waiver affidavit applicants should have accomplished at least 50 flights on a high performance model."
The next one answers one of your specific questions about rotary wing turbine sign-off requirements.
"The pilot will successfully perform a qualification flight consisting of all flight maneuvers from the Turbine Applicant Flight Demonstration under the supervision of two experienced turbine pilots, one of whom is a contest director. A Designated Helicopter Contest Director is required for rotary wing applicants
More AMA documents regarding turbines here:http://www.rcturbine.com/html/ama_waivers.html