Brick:
@1: if the pads move less, than I would think that the 'system' is move vulnerable to imperfections, with rimbrakes your wheel can have a slight wobble, but with discbrakes your rotor has to be perfect (more or less), otherwise you'll rub your brakes.
@2: I've never heard of it happening either, and for the OP's purpose it's probably not a problem.

but, if I where to build a bike to take me across the world, I would like to know what would be the best option in the strength department (in the availability department it's probably still rimbrakes I imagine).

again: I'm not against discbrakes, I definitely like the idea of having brakes that function well in the wet (at least: better then rimbrakes), especially important for commuters.

(btw, sorry for threadjacking, I'll create a new thread if it's a problem)