Hi, I am sorry you are dealing with a mold problem. It sounds like you have already taken some important steps to prevent future mold problems, by installing intake vents. Before I continue, I do want to note that the advice I give pertains to areas of mold smaller than 10 square feet (about 3 feet by 3 feet). For areas larger than that, I'm less able to help, but I have included some resources below that I find very helpful. You may find the third link to be most helpful, as you can compare the recommended guidelines with the plans you received from the three companies. 

For your second question, insulation may help prevent a reoccurrence of mold. Insulation should help regulate temperature, and prevent condensation; by reducing moisture in the area, you reduce the likelihood of mold. 

If the areas of mold are small, and you want to clean them up yourself, I do have some suggestions, available at the first link. The first link is a website associated with my research center; we get asked a lot of questions about mold, so we created this resource page. 

• https://ehsc.oregonstate.edu/resources/mold-and-mildew
• https://www.epa.gov/mold/mold-cleanup-your-home (For areas less than 10 square feet)
• https://www.epa.gov/mold/mold-remediation-schools-and-commercial-buildings-guide-chapter-1 includes remediation guidelines that companies should follow (Table 2). 

I hope this is helpful,