They're not stupid. But they're big! Linux, and unix in general, is a little opaque at first but with a little reading and experimenting you'll be up and running before you know it.
Have a look for some general "linux for beginners" sites. The linux documentation project
will teach you plenty.
1. Don't know much about Java, but the downloads from the sun site will work with a little research - I got mine there. But you might want to leave this until you've answered the other questions.
2. an rpm is how redhat installs and maintains packages (programs). "man rpm" will give you plenty to read.
3. This was covered in this site lately - use the search function.
4. Using rpms (see above) or using tarballs - "man tar", and always read the README files (get familiar with the basic commands first though).
5. There sure is. It's called an xterm (hit alt-F2, then type xterm). The two most useful commands are "man" and "apropos". Start off with "man man" and "man apropos".
Sorry if this seems a little short. I do mean it to be as helpful as possible but a full answer to any of these questions would take a long time.
Good luck and have fun!