The "idiot Whitecloak" was definitely Galad--someone who saw past his own faults (seeing the world in white/black), acted out of character, and ended up supporting Perrin. Neither Perrin's camp nor the Whitecloaks would have survived that assault had they not worked together (something BS didn't really show too well in the fight IMO).

The trap was actually a pretty damn good one. But it's unfortunate that Graendal didn't realize how strongly ta'veren Perrin is. I don't understand why Graendal didn't just skip the whole Dreamspike ordeal, gateway to Perrin's camp, and kill him with the TP. Perrin's not a channeler--he has been by far the easiest target for the Shadow this whole time (Mat's medallion and his close affinity to Aes Sedai have somewhat protected him from this type of assassination).