API + Software + More -- 2

I am looking to get the following job done if this is possible: I am seller of brand item clothing, shoes, accessories etc. I need to get all my stock information which I receive from my suppliers updated on Amazon Marketplaces UK, Germany, Spain, France & Italy. I also need to get the same done on 2 WooCommerce based websites. One of those websites is completed, the other one is currently being build. There are more sites to follow after this. My current supplier offers the stock updates in several spreadsheet formats, but a Magento version is also available and can be purchased if necessary. The supplier updates every 15 minutes. Now this info needs to be taken, processed into the various formats for Amazon & WooCommerce so that the stock levels can be updated every 15 minutes automatically. Currently I have to do it all manually, but I simply can no longer find the time and it needs to be automated. Also, I would like, as part of the same process, any customer orders from Amazon and the websites to be automatically processed directly at the suppliers. This is also something I am currently having to do manually. A day after orders have been processed my supplier issues tracking numbers via DHL on all orders. Those have to be passed on to the customers on Amazon and the websites. Again, currently I am doing this manually, it needs to be automated as well. Also the customer details need to be saved into a spreadsheet or accountancy program for easy processing of quarterly taxes. Furthermore, even once this job would be completed there will be a stream of continues more work as I am planning to add eBay to this as well as several more websites, plus more and more suppliers which would also have to be connected into this system. I need this doing so that I can free up 6-7 hours of manual labour every day so that I can concentrate on creating more business by adding more and more sales platforms as well as suppliers. To me this seems quite a large undertaking, plus it will offer ongoing work for the right person after the main job has been finished. I am sure there may even be a few things I have not even thought of as yet. I look forward to receiving your ideas and how you would envisage completing this job. I would prefer a fixed job price for this if possible. Kind regards, Michael Bruckner