chaff and flares are not likely to work in space.
Chaff relies upon the ait and wind to spread the foil, the larger the foil field, to a point, the better job it does. no air = no wind = ball of aluminum foil.
Flares would have another problem with, no air, no fire, no fire, no heat source, no heat, no decoy.
ECM in wcp would be just that, ELECTRONIC. they would most likely create a large Electo-magnetic field, this would throw off tracking systems, other than IMRECs, and would also create a large heat signiture. how ECM's can decoy an IMREC, i do not know, or have an idea, as of yet.