Shell width should be 73mm. Spindle length determined by your crankset. Why not just pull the old one out and see what it says on it, or have your LBS do it (or ask them)? Your bike should have an ISIS bb, get used to changing it yearly.
Yearly? I've put 12,000km on my vertex and the stock shimano BB has been changed once. I'm not even sure it needed it, it was more of a make-work project, and the old one still seemed smooth once I got it out.
I guess I need to ride that thing in the mud more often.