One question at a time:
Q: I did a search on washing yeast but did not find what I am looking for. What I want to know is what is the best method for recovering the yeast.
A: Try a search for "yeast washing". There are plenty of hits. Harvest your yeast after you rack the beer into the secondary.
Q: Is it recovered after primary or secondary fermentation?
Q: Is it best done by siphoning it off or pouring?
A: Boil and cool a minimum of 1/2 gal of water. Pour it into the primary and swirl it around to mix the trub off of the bottom of the container. Pour that into a gal jug for seperation.
Q: How much should be saved?
A: All of it. The trub and yeast should seperate during the process. Discard the trub/sediment. Save the yeast.
Q: I assume it should be refrigerated until the next use.
A: Correct. Once washed.
Q: What is the best method for reactivating?
A: Make a starter.