On the leading / trailing caliper thing, I think most bikes have them trailing as a safety feature.
As we all known, aluminium is a pretty weak metal. And braking forces are considerable. With trailing calipers, the calipers (and/or their brackets) push against the entire fork when they grip the disc. If the calipers are leading, they only pull against that little aluminum mounting point. Hello, fatigue and catastrophic failure!
If you want an example of a caliper that pulls against its mount, check out the torque arm on the rear brake. That's a substantial lump.
