Modify an Online Store - NEW

I've installed a [login to view URL]'s version 3.60 ASP.Net template CMS site on my Windows 2008R2 hosted server and got it up and running. Please study nopCommerce to fully understand what it already includes, feature-wise. THIS PROJECT Modification to nopCommerce 3.60 C#.Net code and SQL Server 2014 table structure. (see attached "[login to view URL]" of idea for home page of new site) Want a "Directory of Information" like a combination of austin360 and Craigslist for "customers (buyers/sellers)" to list(sell)/find(buy) lodging, products, events, food/restaurants, employment, etc. So I need a super flexible category/subcategory system. Later, if we work well together, other parts, like manage/display banners at top, and many other features will be needed. Note regarding pmt systems: (A) nopCommerce has robust built-in payment/cart system. (B) MY [initial] version will only need cart/payment for customers(sellers) to pay the site owner to list(sell) their products/services/banner ads. The rest is like Craigslist in that people search the site, find a product/service, and are connected (contact info and/or URL) with the advertiser of the product/service. Later work will add more situations where online payment is needed. CATEGORIES (see "[login to view URL]" for idea of how I imagine added tables to look) In nopCommerce, for any category there is only one parent category possible. NOTE: There is surely a fair amount of code site-wide that use the Category table's ParentCategoryId field. Want: (See "[login to view URL]") (A) Categories/subcategories to have ability to have multiple parents. (B) Infinite levels of subcategory "tiers". (C) Any cat/subcat can have Parameters. LISTINGS This is the part that is most like Craigslist, where a "posting-customer" wants to do anything from list his pool cleaning service or restaurant to one time events like concerts or yard sales to individual used products like stereos or automobiles. This is why I believe we need the above changes to the category system. My client also wants the site to charge posting-customers nothing for first x number of characters but after x, charge $____. Other modifications to price for this "product": -- $___ depending on how long a post (ad) will stay up. -- $___ additional for image(s). -- $___ additional for URL link to posting-customer web site.