This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
It sounds like you're building up a strong Java skillset there.
No EJBs are needed for a Struts application - no need at all.
As far as servers go, you need to be able to deploy a war, so you can buy a WebSphere Server, or you can download a Tomcat server for free. Any environment that runs a Servlet/JSP app will be capable of running a Struts App.
If I may suggest, I have a few very simple, multimedia tutorials on Struts on my website. It takes you through creating a Struts app, handling forms with Struts, providing user feedback, and i18n with Struts. There are changes from one version of Struts to another, but this is the hardcore Struts stuff that doesn't change. Check it out:
If you know JSP and Servlets then you are 90% of the way there to knowing Struts. Struts (along with the Struts custom tags) is really a fairly thin layer to help out with the more mundane aspects of a JSP/Servlet solution (like populating files on your jsp, validation, page flow and retrieving stuff out of the request).