Organise my xml,txt and csv data feed in my shopify store

I have got a shopify store. Our Suppliers have a data feed that is same on two suppliers and is changing on the third one. Also the data feed needs images alt to be checked. How do we update the inventory from our suppliers everyday. I have got all the categories and subcategories sorted according to the suppliers . Tasks that needs to be done 1) How to update inventory from our suppliers everyday. 2) Improve SEO on the website. 3) Better and a simplistic way for updating the inventory and the Outdated products in shopify are required. 4) If we need to simplify the category list and the sub category list are welcome. Please read the above information carefully and give me the solution according to it. I can provide you the details once you give me enough information.