Spork,

The first step is to determine where the moisture is coming from. It
could be from the outside and you need to do something with drainage
(landscaping, gutters, etc.) or wall repair. It could be an interior
problem with cold water pipes sweating and general humidity. Insulate
the cold water supply pipes with foam sleeves. It's most likely a
combination of the two.

Check with your local building code authority to see what they
recommend. Some cities have that information on-line. In my part of
Minnesota they now require two vapor barriers; one between the
exterior wall and the interior insulation (just up past the ground
line) and another one between the insulation and the full finished
interior wall. Space is left at the top to avoid the moisture
sandwich. This is a recent change from just an interior vapor barrier
(the Canadians have been doing it with two for years).

Watered down bleach will do a fine job killing the mold and it won't
come back if you solve the original problem. Foam boards properly
sealed with caulk and the small cans of foam should do the trick, but
then you do need drywall as the foam burns easily. Don't leave the
windows open if you're running the dehumidifier. If you can air
condition the space properly, you don't need the dehumidifier.

Good luck.

dss