Comments on invoices and prepaying customers

Hi

  1. Is it possible to add comments on invoices that will be visible for purchasers ? Can it be stated on any reports?

  2. Ive learned how to handle prepayment to vendors. ( http://blog.mohamedaamer.com/microsoft-dynamics/ms-dynamics-ax-2012-prepayment-processing-2/ ) Is the any way to deal with prepayment from customers?