Adding and Getting specific report on products offered as a gift


So for my company with every product A sales invoice i make i provide 30-40% as a gift.
For example if i sell them 100 of product A i give them 30 of product A for free on top of it. My questions are.

  1. Can i add part in sales invoice where i add a product i specify how much in number or percentage i want to provide as a gift. Without having to add the product again andits value zero
  2. Add a reportin mechanism where it would how me how much i have provided as a gift.
  3. Have a notification if i exceeded a certain gift limit