Not sure if this is right but I know that Garlands pot was first descended on Castleton Garlands night.. so I've always assumed that St Valentines was first discovered or passed on the 14th of February.
AFAIK.. filthy five is rigged off new ish bolts but you can only access it from the East canal. St Valentines cannot be bailed and the syphon system doesn't work. I have a half built pump in the garage and the promise of a deal on sone pipe from rob eavis but have still not got round to sorting it!
Not sure about the Devil bit... but "the windpipe" as I've always known it lies in the passages above the crabwalk. Its a long low flooded section where there is just enough airspace to keep your head out the water if on its side. You may get a wet ear. You have to pass it if your doing the round trip.