The Downpayment funds come from a pre-existing pool of money owned by the AmeriDream Charity, and not from the Seller. NO, anyone can use it. Participating in the program, makes their home available to a larger number of buyers. More buyers, means less time on the 'market,' which can actually save them money in the long run. Also, in some instances, but not all, Builders or Sellers 'negotiate' on the price of pay for some of the 'closing' costs.
Builders sometimes give away 'extras' or upgrades to make a sale.
Chances are, they won't be able to do those things and participate in the Program.