The yellow stuff dripping out of the paint is probably the alkyd binder in the paint that is leeching out. Often times latex or similar paints are painted over oil-based paints, which should reall...

You cannot tell if 311 is the right option until you spray/scrub with bleach first. It's possible it's not from a leak at all, but from condensation from a cold exterior wall vs. the heat of the r...