A.1 multichannel should be used only w cmyk if outputting seps. Start with a blank CMYK canvas and pile your PMS channels on top of that

A.2 NO, save as cmyk eps, dcs 2.0

A.3 see A.2

also, make sure to maintain consistency in your naming and using of color. Dont use Pantone Black in PS, then normal Black in Freeh. It sounds like you're using PS 5... is that the case or are you in 6? Not sure if multichannel works the way you want it to in PS5, but i could be wrong. Retrocity?
Good Luck!