Automated Magento XML Data Import & Export System from POS Software

REQUIREMENTS: Develop an AUTOMATED integration between Magento and Windward System 5 POS system (WS5). Be able to export the 3 x xml files from WS5 and import into Magento daily. Be able to export sales/customers and item stock from Magento back into WS5 daily. Do all this automatically by using a script or cron job server side, and some sort of script or macro on the WS5 desktop computer. BOTH ends must be automated...... i.e the extraction of the xml files as a .zip from the WS5 desktop computer, it uploads the .zip to the website, extracts it an processes the updates. In return, a script extracts data from Magento and sends it to WS5 to update it. This is a 2 way data exchange daily or as often as required, even hourly is OK. MOST of Magento item features WILL be used, and the styling must be good, especially for the description. Magento store will be ALREADY installed, themed and designed, this is NOT design work, this is purely programming and interfacing work. Information about Windward System 5 WS5 is a POS system, it has xml capability. It can integrate with e-commerce. You MUST give me a DETAILED explanation of HOW you will accomplish this task and that you understand the requirements. "WE CAN DO IT" is NOT good enough! All scripts and software become MY PROPERTY, you must hand over ALL code to me upon completion. If any extra software need to buy like magento import export plugin .. We will buy that.