Hi
I think, as a PM, you should concentrate more on getting awareness about things like:
1. Various frameworks widely used around java viz. Struts, Spring, Hibernate, cactus etc.
2. Varous tools being used in Java development viz. Ant, IDEs(Eclipse, IDEA IntelliJ, JBuilder etc.), JProbe, JProfiler
3. Typical problems/issues being faced in Java projects.
4. Getting right resources into Java projects and indentifying and replacing unsuitable resources from projects.
5. Typical hardware and software involved around Java projects(RAM, Application servers, Webservers, Databases etc)
Let me know if you want more information
www.j2eequestions.com