Hey James,
Well there are some very long answers to your questions, but I'll try
to keep it brief here:
Yes, Minix is a complete operating system.
Yes, it is like Linux (in behavior) as well as other POSIX-like
systems, but it also has a major difference in the architecture of it:
Minix is a microkernel, where Linux is a monolithic kernel. If most
of what you do is user programs in Java, then this will probably make
only a very small difference.
I do not know of any JDK for minix, but I am not a Java programmer, so
maybe someone else can give you a better answer. However, if you are
interested in this you could try to port some Java functionality to
Minix, and the community here can support you.
Yes, 'the Minix book' as it is commonly known is 'Operating Systems
Design and Implementation':
http://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmI
And the best way to learn more about minix is to use it. The wiki has
some really good instructions for setting up Minix in a virtual
machine:
http://www.minix3.ucsc.edu/wikis/minix3/en
Hope this helps, and If anyone knows more about the state of Java in
minix, I'd love to hear it too.
~Alex