Create Javascript Widget that Updates

I would like to have a web widget created where I can update items in one place and they will automatically update anywhere I have placed the javascript widget code. The widget would be sized 300x500 with about 4 product items. The items would have an image, text, and outgoing link. You can scroll to the next page that will have 4 more items. I would need to have an admin area where I enter the data such as image, text, and link. Once that data is saved, it should automatically update the widget. Optional: Once the javascript code is generated from the items I entered, I need to be able to track the websites that use my widget so I know where the links are coming from.