I haven't looked at the java implementation so I'm not entirely sure what it does, but here's an explanation of QBX. If any of it is hard to follow, I'd recommend checking my C code it's based on, which doesn't have all of the speed hacks in it (courtesy of Tomas Rokicki, otherwise it would be unbearably slow). You can browse
http://bitbucket.org/emg/cubeutils
The transition tables hold a single turn for each face, if you want to do 2 or 3, apply that transition 2 or 3 times, but we never apply more than once at a time anyway, because after each turn we search down that branch, before coming back and just doing another turn.
As for the pruning tables, there is one for each coordinate (co, eo, ud1, cp, ep, ud2), no bigger tables based off of multiple coordinates.
The solution length will generally be a bit longer than say cube explorer, because we only find a single solution, instead of trying more phase 1 solutions of increasing length in order to find shorter overall solutions.
In the future (perhaps distant, we shall see) I hope to have the option of downloading larger tables as opposed to generating the small ones on load I'm also looking to add the ability to search for shorter solutions, much like cube explorer does, with the play/stop button by each cube.
-emg