yes, you can but I think that OpenDS is better for you
there are no special problems with using Oracle products with Jboss AS, as long as there is some way to communicate with them.
For database there is no special restrictions, for version compatibilty the most important part is JDBC driver, which you can download from oracle's website, Oracle has very good jdbc support so there you should not find any issues.
LDAP is standard protocol and becouse of that it can be used with any product that knows it, java and jboss are among them
How it is with SSO I have no personal experiance but i would think there should be no problems beyond maybe writing some small parts to comunicate with your system.