Physics: TickSec and keeping track of time

I am implementing some Verlet based physics and was wondering how other people have implemented dt (delta time). Right now I am using TickSec which looks like a constant defined in gamebase.h that assumes that so much time will pass between calls to processtick. I want to do a time corrected version of the Verlet equation, but TickSec will not change between calls to processtick.

1 Am I making this more complicated than necessary?
2 Is there a timebase that I can use that has some decent resolution to give me meaningful data?
3 Will doing this help keep my sim between machines in sync?
4 In practice is TIckSec good enough?

Thanks,
Frank