Stock Trade Billing System

We are looking to create a billing system for our company. Clients trade stock and are billed on a variety of factors including the total amount of transactions for the month, the price of each transaction, where the trade was routed through, and other monthly fees. The system must be able to change the rates and fees mid-month and save the dates of the changes as the bills must reflect the correct price at the time of the trade not the time of the bill. Users will load daily .CSV trade files. System must calculate transaction totals - on a monthly basis, system must calculate final bill. Summary and breakdown is required on bill. Language must be C#, MSSQL 2008 R2 DB. All code must be fully documented Users must have the ability to ADD/REMOVE clients, users, destinations. Users must be able to modify Destination rates, client rates, and fees. Please see attached specifications. There may be additional tables needed, however workflow and process should remain the same throughout project. Please ask any questions if I am not clear.