Customize products section in Sales Orders

Hi. I have two questions:

I want customize products related list in sales orders to replace discount and tax columns with other product fields. Is that possible? When I go to costomize module is not option to modify this section.
When I create a sales order with new sales order option inside purchase order, the new sales order inherits the purchase order subject value. I need account name and vendor name inherits too. It's any way to do that?

Thanks.

Carlos