I have a 34-2 with a Yanmar 3GM30F, and my blower also has never worked. I kept an eye on heat down there, but it never seemed an issue and I have stopped monitoring it. The engine seems to get plenty of air to run, but I also always have the companionway open when running it so maybe it's more of an issue when everything is buttoned up (e.g. in bad weather.)
Re: the vent hoses... if people mean the little fittings on the transom (not the big "dryer-vent" one connected to the blower tubing), you better get those right -- one is the overflow for the fuel tank and the other is a fuel tank vent line. You do not want those disconnected... then fuel could end up in the bilge at some very inopportune time. Aside from being a hassle, from reading reports from sailors caught in nasty storms it sounds like fuel in the bilge is pretty debilitating in bad weather -- there is no escape in the sealed-up boat, and the fumes make everyone feel terrible at the worst possible time. I can't remember if it was a 1979 Fastnet race report where I saw something about this*, but regardless, you want those lines connected to the outside, vent openings facing down, and not leaking.
* There is at least one 79 Fastnet racer on this forum; they can add comment if they want to / know.