If I remember George Fix's article correctly the FWH were added when the wort had covered the bottom of the pot, they were comprised of the late addition hops, and increased the IBU's about 10% above the control. The also tested this on pilsners, so you are gtg for that.
I personnally do as many others do, pull about 1/3 of my "flavor" hops and use that for FWH, leaving my bittering hops in place. You leave the hops in the entire boil.
I do not put hops into the mash, I have read enough to indicate it is pointless to make it not worth my while; however, I suppose a good side by side experiment would be in order to really know.