Custom features on openerp

I need to custom our ERP system OpenERP by modify some features and this is the list of these features: - previous balance in every order and have at least 5 previous move with possibilities to give us alert - in purchase requisitions show to data entry at least the last purchase price for every product ( recommended to show 3 previous price ) - the possibility to send to the partner email when the finance enter new account entry evolve him/her in the entry - give us the margin base on the last purchase price not base on the saved cost price - report that show us all the purchase price for the product and export it in excel file (NOT PDF)