What kind of Java expertise would I need to have in order to successfully deploy and keep my campus instance of the portal running?

In general, over and above a working knowledge of and substantial experience with your chosen application server, you really have to understand the issues related to server-side application deployment and support in a modern, web-based environment. If you understand how to start, stop, and backup your your application server and a database server, and how to deploy a JSP 1.1/Servlet 2.2-based web application, then you know enough to administer a uPortal instance. Your application server vendor will be able to help you on this front with training and documentation if you don't.