My EPDM roof maker recommends against coating the roof. I know there are different makers and recommendations but I only wash mine about once a year and check/reapply the sealant as needed. the chalking of the roof material that was left on your fingers is normal wear. Keeping it sealed well with the Dicor lap sealant is critical as it cracks over time. From the pics you supplied the sealant and roof area that has pulled loose needs to be addressed immediately. BTW, these are items I consider routine maintenance.
