I can't figure out how to create a solution in Visual Studio 2010 that will allow me to alter existing lists in a SharePoint 2010 site. Specifically, I want to add a new column, which contains a small icon, to existing document library lists. I want to be able to take an action when someone clicks on one of the new icons. I also want this new column to become part of the default view for new document library lists. All of this needs to be easily deployed to a SharePoint 2010 site via a .wsp file.
Extensive searching on Google has shown how to create new lists and new column types, and how to programmatically add columns to one of the new lists, but not how to modify all existing lists.
I'm brand new to SharePoint, and any pointers towards a solution would be much appreciated. Thanks!