Linux -> linux remote X login/desktop

Connecting over the network (e.g. with SSH) is by far the method that has the best chance of working and the least chance of causing damage that might otherwise be avoidable (such as killing your X session).

If the mouse is working but not the keyboard, it means that X is not completely hosed. Try plugging the keyboard out and back in: this can help if the problem is in the keyboard driver. (It rarely is.) If you have a root terminal or can get one without the help of the keyboard, try typing chvt 2 there (where “typing” means copy-pasting the letters).

Another thing you can try is the magic SysRq key: press Alt+SysRq+R to switch the keyboard away from raw mode, and try Ctrl+Alt+F1 again: this time the key combination should be handled by the kernel and not by X.

Well it actually depends on your desired goal.

Do you want to distribute load (and client requests) between both of your webservers (multiple active arch) or you just need to be "fully" redundant in case of webserver failure?

If you just need the redundancy aspect and are not worried about distributing load I would suggest using pacemaker to achieve this.

You basically have to define resource groups for jboss and the other services you might need running and define a single VIP that would work as the redundant point of entrance for your active webserver.