CUBECART MODS

Looking for a cc mod to do this. Part I) If you have already downloaded the item it does not allow you to download it again. (email gets sent, saying when you did, download it {date time}) Part II) Imagine that you have 5 products, I want to have the mod, ONLY allow the download of ONE of the 5, (again if tried the email gets sent you have...) Need it expandable, in that its a simple mechanism to add another product to this "group of 5" Part III) That (look at killer skin tabs) the only One tab(category) would contain downloads, that tab being enabled, and only that one, which would be defined by the user name that they logged on with. The other content for the others tabs(categories), would have no content. Eg. you could select it, but it would show that there was nothing there. There would have to be an admin tool, like "add user to category" And one tab(category) that any user could see. Steven