excellent assessment foolishfish.
ahhh... the joys of mold remediation... tyvek suits, respirators, zip walls, air scrubbers, specialized hepa filtering vacuums and irq 8000. almost makes a mouthful of microban from a failing pump sprayer seem appealing. however did you pry yourself from such a rewarding career of crying, wining, moaning clients?
Oh we did it all, Asbestos, lead paint, pigeon and bat guano. Thankfully I was the Operations Director / Project Manager so I didn't actually have to do much more than tell others how to do it...and no I don't miss it. I ended up being poisoned by solvents and cadmium among other things. But as usual I digress.
Warm moist air wants to move to cold dry air. The higher the differential between the two the more persistent the effort. At some point in this migration the water vapor contained in the warm moist air is going to find its dew point and begin to condense. The purpose of a vapor barrier is to try to keep this point as close to the conditioned space as possible. Ideally this would be the face of your walls and ceiling.
I say ideally because the presence of the moisture and mold where you can see it is much better than halfway between your siding and drywall where you can't. At least seeing it gives you a chance to respond before mold starts eating your house.
Since you're in R.I. I'm going to take a guess and hope that your case is one where the original vapor barrier was properly installed, (usually up there I believe they favored poly attached between the studs and the drywall) and functioning as intended, hence water dripping off of the walls because it has no place else to go.
Seal the tanks as best you can, wipe up any standing or obvious water everywhere that you can, check to make certain that your dehumidifier is working properly and get a hold of a couple of fans. My newest dehumidifier will pull the relative humidity down to 35%, which is actually a little past the dry end of the comfort zone but fine for this purpose. It just means that the darn thing is never going to hit its set point and shut off, and you will see it on your electric bill.
BOCA (the basic building code that most jurisdictions have adopted in one form or another) requires that new buildings that use gas burning appliances (stove, water heater, furnace, etc.) must be able to draw fresh air for combustion from outside of the building envelope. This is because many new homes are as tight as the old V.W. Beetle, meaning you could pop an ear drum slamming the door because they've finally started building structures that don't leak air like a sieve.
I don't have the info. available right at this moment but Honeywell sells a variety of controls and dampers that are used to control the intake of that combustion air and can be cheaply adapted to humidistat control for a kind of poor man's air exchanger. There are also companies like Conservation Resource Technologies that handle a variety of ventilation components that deal specifically with moving or exchanging contaminated in door air:
http://www.conservationtechnology.com/building_ventilation.html
There are paints, Kilz alcohol based primer for example, that are impermeable enough that they can be classified as a vapor barrier, if you should find out that the moisture is in fact getting into your walls. Be warned that if you attempt to use this stuff indoors in the winter it will kill every living thing that breaths the fumes, including your fish, and it is violently combustible. It is only to be applied with the utmost care, personal protective equipment and fresh air ventilation.
Buy some blow dryer shrink wrap and double faced tape to cover your windows, even if they are already thermally insulated, and try some non-aerosol WD-40 on the rusting door hinges. If you don't need the natural light you can also cut pieces of rigid foam insulation board and cover your windows with it from the outside. Looks like hell but it works and will save you a little heat loss in that room.
I'm sure I'll think of something else later but I gotta go. Good luck.
