0) FAQ - http://www.jboss.org/wiki/Wiki.jsp?page=FAQJBossJMX
1) FAQ - http://wiki.jboss.org/wiki/Wiki.jsp?page=HowDoIAddANotificationListenerToARemoteMBeanServer
2) You can write your own mbean, extending ListenerServiceMBeanSupport that simply re-emits every received notification. You'll deploy this on the server configured to listen to any notifcations your want. The from the remote client you will just subscribe for notifications to this mbean. You need to be careful, so the content of the notifications emitted is serializable.
I'm using HTTP adaptor for MBeanServerConnection. There is API "addNotificationListener" on the MBeanServerConnection -- can I simply use this to add my notification listener to the remote MBeanServerConnection?
I don't think this is supported. Maybe you should have a look at the new JBossRemoting project in case this is solved there.