Perfex CRM Customization - Stock Control

I'm looking to add a simple stock control. I want to utilize what is already built in so job will require adding new features (Preferably as a Perfex add-on Module and few changes to original files if required) 1. Under Sales → Items modify ‘Add Items’ form to include tick box ‘Trackable Inventory’. When ticked it allow user to add additional data (quantity, rate/unit cost, location, serial number). 2. On main screen Sales→Items add column ‘Qty’ & 'Location' that will show value from items quantity field and location. 3. Small customization in Invoice screen (Sales->Invoice). Basically, when adding products/items from build in dropdown to show quantity next to the item. When such a ‘trackable item’ is added into invoice and invoice is saved than to subtract items qty added onto invoice from items list. E.g. I have 10 LCD TVs in my Items list. I create new invoice and from dropdown select LCD TV item and change qty on invoice to 3. I save an invoice. At that moment my LCD TV stock on Items list should be updated to 7. When I cancel or delete such an invoice all items and their quantities should be updated on Items list. E.g. Cancelled invoice with 3 LCD TVs on it, so my qty of LCD TV item on Items list is changed back to 10. 4. Small customization in Invoice screen (Sales→Estimates). Basically, when adding products/items from build in dropdown to show quantity next to the item (screenshot attached). Once the estimate is in Draft, Sent, Accepted status to substract qty of an items added, and if it's Declined or Expired to update items qty accordingly. 5. Add new report under Reports to show/filter items based on Item Group and display current QTY of the stock, price, location, VAT etc.