Pretty sure 44 and 55 (so, the number following a driver's name) is just an index... start a server and the first person to join is 1, second is 2, etc. Gives you a differentiation between two drivers with the same name I guess. From what I've seen a driver who leaves a session and returns still gets a new index (rather than retaining their old one).
The number specified in contact, I'd be taking a guess, but it's something to do with the magnitude of the contact - smaller values are related to light taps, larger values (up to 1) seem to be heavier. Whether it's somehow a reflection of the calculated impulse (seems unlikely, because the value is never greater than 1.0) or the 'directness' of the impact (perhaps glancing hits are lower?), I'd only be speculating. Hopefully someone with more idea or experience can answer that one.
