mold has to get from the wall cavity into the air in the house before you can be exposed to it. however, that does not mean that it’s good to ignore the mold if you know you have it somewhere in your house. the mold will continue to grow (as long as it has water), eventually damage the building and increase the chances that you will be exposed.
that depends on how much mold is present and where it is located. if there is only a small amount of mold, such as in a bathroom or kitchen, scrub the moldy area with soapy water, rinse thoroughly and allow to dry. if 