I know I'm late to this but I figured I'd give my experience incase it helps someone else who finds it. I'm a big fan of cycling capes. I've got a clever hood and a carradice. They keep the rain off while preventing overheating. I find my legs get wet so I wear rain gaiters or tall rubber boots
I tend to prefer the carradice due to how stiff and quiet the fabric is.
Underneath, I wear the same cold weather gear I would wear normally. A warm wool sweater is usually plenty unless it's really cold in which case I'll wear an unzipped windbreaker over the seater