Customer store credit balance, sort by top sellers/most popular, shop by sizes, sitemap

Magento enterprise 1.12.0.2 ecommerce website with several small issues to fix and functionalities to activate. Once implemented, need to be tested and verified working properly. Tasks: 1. Customer store credit balance: customer credit not activated on the backend. I can go to customers >> manage customers >> customer name >> store credit >> update balance. But once I update the balance, it does not show up in the customer's account information and it also does not adjust their credit balance. We are currently circumventing this issue by issuing unique voucher codes as store credit. 2. Sort by best sellers and most popular: customers should be able to sort products by top sellers and most popular (most viewed). These results should only include items that are currently in stock. 4. Shop by sizes. I would like the customers to be able to shop sizes by small, medium, large. I would also like for customers to be able to shop by shoe size in the footwear section (5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11). Again, this "shop by" widget must check inventory before displaying results. 5. Sitemap. My google webmaster tools account says I don't have a sitemap, but there is a link on my website that shows I do have a sitemap. When I submit and test my sitemap url to google webmaster tools, it says that there is a general error, "Your Sitemap appears to be an HTML page. Please use a supported sitemap format instead". I need the best sitemap to be generated. This should include different types (html, xml, txt, and gz) that are validated by all major search engines (google, yahoo, bing, ask, etc...). I'd like it to have other features such as pinging major search engines, identifying dead/broken links, no limitations on page size or numbers, automatically split sitemap files, optimized scheduled sitemap creation, automatically creation of and linking to [login to view URL] file. Upon creation of completed sitemap, you must upload to site, and I will run google webmaster tools sitemap test to verify. ALL: these changes must be made on the mobile site as well.