Per site, list driven footer and other content areas on a SharePoint 2010 master page?

Question

So I worked with a vendor to provide a js, a powershell script and <div> content holders in a master page that would pull the content dynamically based on the site or subsite, and more specifically from a custom list in that site. To explain, if I
have a root site collection but want to be able to have the end user control the site content, such as a custom top navigation (above the global) and custom footer, and custom place holder content that would appear under the navigation; I would like to have
that content pulled from a list.
My goal is to not have a "custom master page" for the many many sites we have in our environment. I am using twitter bootstrap as the foundation for the master pages, then a set number of page layouts pending whether they want left nav to show
or not. I also typically just use the v4.master for the system pages, but am not sure if that is a best practice either being that the list display forms for a publishing site are ugly so need customized per list.
Has any one done anything like this and if so could you point me in the right direction? Any guidance would be greatly appreciated. Right now am working within SP2010 but will be testing for SP2013 in the near future. 

Answer 1

Hi,
Based on my understanding, you might want to display dynamic content in the pages which reference a specific master page, the content stores in a custom list, users
can update the master page by updating the corresponding list items.
Then there would be two main steps in a solution like this:
1. Data retrieving of a list: JavaScript Client Object Model can help to query the needed items from a list;
JavaScript Client Object Model
http://msdn.microsoft.com/en-us/library/office/hh185006(v=office.14).aspx
More information about JavaScript Client Object Model:
How to: Create, Update, and Delete List Items Using JavaScript
http://msdn.microsoft.com/en-us/library/office/hh185011(v=office.14).aspx 
2. Modify the master page: With the data retrieved, we can then change the HTML source code of a page using JavaScript.
About how to
modify the HTML using JavaScript:
http://www.w3schools.com/js/js_htmldom_html.asp
http://njarb.com/2011/06/update-html-content-using-javascript/
We can apply the custom JavaScript to the master page, then when users open a page which references this master page, the JavaScript will run, get data from the custom
list, change the HTML source of the current page and display the content you want.
Best regards,
Patrick
Patrick Liang
TechNet Community Support