vTiger 6 SO Module Customization

I would need some work to be done on the SO module. My current setup has one custom field in Products, named "cost", which contains the product cost in USD. What I need the SO module to do, is: -it should allow entering each item's costs and select the cost currency. Entered/Selected values should be stored in DB in the corresponding SO. (pull default cost USD value from product custom field, show currency select drop-down (default: USD), allow for editing the amount and currency while modifying the SO) -Then the SO module should show gross profit per line item in % (match cost with selling price currency!) and write cost and profit value to SO in DB. - SO Module should show gross profit for the entire sales order combined at the bottom, next to TOTAL (total SO invoice value minus summed up cost of all items and shipping/tax payable). Values should be visible in exports done by PDFmaker, and in SO view. All calculated data should be stored in DB. Will have more jobs to be done soon, as many aspects of Vtiger are not matching my requirements entirely.