This has likely been addressed and I just missed it and am n ot finding it in a quick search. When rolling for an attack the net successes are used as a bonus to damage. What I'm not 100% clear on is if this is 1 success is used to hit and remaining net successes are used for damage boost or all net successes are used for the damage boost.

That is. If you roll say 2 failures and 5 success you have net 3 successes. Is this +3 damage or +2 damage?

+3 damage.

Too many of us are programmed by other game systems, so this simple concept is hard to grasp at first. It's # of successes plus the base damage of the weapon. It's easier to add # of successes then to add # of successes -1. You can't (without soak or some other factor) actually get damage equal to your weapon damage.