Can anybody tell me how long the affects of black mold exposure typically last?

Varies. This would vary depending on the sensitivity of the person involved with the dose of the exposue being a factor as well. I would expect that removal of all exposure to the black mold as well as providing for elimination of other inciting factors such as dust, dustmites for symptoms to be resolved within 2 to 4 weeks if not sooner.
It varies. Black mold may or may not cause problems, depending on the individual's response. Particularly if one is mold allergic, symptoms will continue as long as exposure is present. With the longer time away from mold exposure, the symptoms tend to lessen, as does the reaction to future exposures. The key to controlling mold exposure is to keep the environment dry, replacing any water damaged material.