I have been hired to maintain a project that is written and maintained in VS 2008. If I purchased a license for Visual Assist would a) the current version work with VS2008 or b) get the last version that supported VS2008
That's really not good. A random thought, are you using browser extensions that might be blocking required scripts or web page components? It's a random thought, but I know that sometimes add blocking and related extensions can break things.
Sorry for all of these problems, that really is not helpful. Obviously if you run into any further errors screen shots of error messages would be interesting, and hopefully helpful. Hopefully though you will have the license key nice and quickly, and can work normally then.