Customize Magento admin order and customer grid

Introduction: We currently have a single deployment on a VPS server. This installation hosts 5 retail shops and 2 wholesale shops. The retail shops sell 1 product (soon 2) and the wholesale sells the same product(s) with the addition of some marketing material. We have several sales people connected to these stores, as administrators with customized permissions, and will both generate sales by calling stores and getting them to sign up and buy online, and also send out orders to be invoiced at a later stage. What we need is a method of keeping track of sales and invoiced sales as well as the relation to each agent. Job description: As a user i can in the orders, invoice and customers section of the magento admin area customize which columns to show and hide. The columns/data fields will function in the same way as the current ones, meaning that I can sort and filter on them. Also when I export the list to CSV the added fields are passed on. Alternatively, If it’s easier, a report function to present the data is also acceptable. As a user I need to have an overview of which orders are either invoiced (purchase order) or paid online and which orders are related to which sales agents, through a relation from the customer to the agent, specified in a custom field for the customer. Basically I need a table populated with the following data - Order number - Purchased Date - Purchased From - Order # - Status - Payment method - Purchase order number - Grand total (ex. shipping) - Amount of product - Customer name - Sales responsible (related to the customer who placed the order) (extra field added with extension: [login to view URL]) The table should be able to be customized to show data in the same way the current order grid allows data to be filtered. A nice to have is to be able to show a net list of all customers filtered on store, total purchase and sales responsible.