I have another question about Medicare plans, what is the coverage of plan A and B for family members and the disabled?
People with Medicare Parts A and Part B can choose to receive all of their health care services through plans that are offered by private companies and approved by Medicare . If you need more info you can read Medicare's page.
and benefits are paid after they are due ? what is this about?
Social Security benefits are paid in the month following the month for which they are due .This means that the benefit due for December would be paid to you in January 2019 , and so on .