Not that I'm suggesting relying on it(competent positioning is more important than anything of the sort), but native job trait activation rate has been increased substantially. I'd eyeball the rate of activation, at least in the case of resist slow and resist petrify, to be in the 50% range.
Its boosted for SURE, in PvP, not sure about PvE. If so, cool.
This depends completely on the tier of the trait you possess, modified by "Enhance" Armors.
Then every + item gives you a separate saving roll with the + added to traits and enhancements. The +'s don't stack but separate rolls are pretty amazing.