I am using odoo 10 enterprise. I created a custom order form in which i want to add multiple product rows. Number of product against each order can vary. I want user to click "Add More Product"  button to add more products in the same order. How to do that in Odoo?

Also i want to set a value on submission of the order. For example: user added all information and products he wants to add against a order and click "Create" button. At this point i want to execute python model function becuase i want to set value of property on create event based on condition. How to to this in Odoo ?

Thanks In Advance!!!