Hi Sherwood,
You will find answers to most of your questions on the Frequently Asked Questions (FAQ) page of Irv Lee's website
Higherplane.
FAQ 9 will tell you what you need to do to revalidate by experience.
Basically you need to have done 12 hours flying in the second 12 months of the two year SEP Rating validity. Of these twelve hours a minimum of 6 must be P1 and one must be with an Instructor (FI or CRI).
FAQ 2 Tells you all about revalidating by test.
Safe Flying,
WKW