Two questions regarding runes and armour

1) If you apply a major rune of, let's say strenght to a Knight's helm, do you recieve +3 strenght from that helm, or only +2 because the rune doesn't stack?

2) Do Superior runes of absorbtion work globally, or only for the applied piece of armour?

You get +3.

They work the same as all other runes, and therefore are global and non-stacking.

Great, thanks for the help.