1) If you dont have sword with Bleeding and wear Roche commando Jacket (10 % bleeding) will you be able to bleed enemies?

2)If you use some Oil (example to add Posion %) and dont have % Poison effect on your sword will you be able to poison enemies?

3)Does your crit effect work only if you have em on weapons, no matter which other bonus (through oils) you apply to them?

It seems all of his questions revolve around the idea of "Do critical effects have to be a basic stat of the weapon for bonuses to apply?"

Any clothing, mutagen, ability or oil will produce the effect, even if the weapon has no critical effect as a basic stat.

And all critical effect chances stack, from all sources.