Gogirlanime, nice research! PM is definitely one of the key sources of phytoestrogens recommended around here, but RC and soy are not. They are usually just minor add-ons to an existing plan. RC in particular is not recommended by Wahaika, but I'm not sure of his exact reasons.
The fenugreek, in th FG-SP-WY combo, is meant to be the main source of phytoestrogens, not to help the body use other phytoestrogens (but you can still take others).
Saw palmetto always works by preventing the conversion of testosterone into DHT, but it has different effects in men and women. In men it's taken to prevent DHT from interfering with feminization. In women it's also taken to block DHT, but the reasons for doing so are more complicated. All the estrogen in the body is produced using aromatase and testosterone. This means that testosterone that is not converted into DHT, tends to be converted into estrogen in females, as long they produce enough aromatase to do so. A diet high in animal protein, as well as the supplements EPO and borage oil, are used to increase aromatase.
WY increases the body's production of estrogens in general, and estradiol in particular. As far as I know, the way in which it does this is unknown. Many people used to think that WY is progesteronic, but the current consensus is that it is not, even if many irresponsible companies still market it that way.
The big three combo comes from Wahaika's recommended plan, which was based on Pammy's plan, which was in turn based on the original Greenbush plan. Here's a link to the plan he recommends:
http://nbelab.proboards.com/index.cgi?board=nbeprograms&action=display&thread=79 (It's the second post)
And here's a link to the theory section of his site:
http://nbelab.proboards.com/index.cgi?board=nbetheory
You should start with the post "basic theory". I didn't really understand BE until I read it.