I've been given the task of developing some extensions for Visual Studio for our internal use. These will have to support a couple of different versions of Visual Studio (VS2008, 2010 and 2012 - VS2005 would be a nice to have but not essential). I'd like to develop these in as consistent a way as possible, reusing as much of the code as possible, while fitting it into the existing project structure for these kinds of tools, which is a Visual Studio 2012 .sln.
What's the best / easiest way of developing this kind of extension? A VSPackage project? Can I make a 2008-compatible VSPackage which is developed in VS2012?
The features I will need for the extensions I'm writing at the moment are pretty basic - I need to create Tools menu commands, possibly a custom toolwindow. My requirements might change later on but I don't need editor adornments or anything like that at the moment.
I saw this question which might seem to be a duplicate, but the answer which was accepted doesn't answer the question, so...