Question: What version of Eclipse do I need for Google Web Toolkit? I see about 7 versions, but none make any references to GWT. Google doesn't mention it to. I did install the PHP version.

Answer: 
Since GWT means Java programming I would recommend the Java (default) Version of Eclipse or Java EE Version because they contain the Java Development Tools which will help you very when coding in Java
I suppose you should install JavaEE version.. Because GWT produce a war file, and it should be deployed to a web application server.