If I have 30% melee reduction and 30% missile damage reduction that means I have 30% overall damage reduction? Because all attacks are classified as either missile or melee? There are no attacks that classify as neither melee or missile? Or are they?
As far as I know and I may be wrong, there are attacks that are purely elemental like Desecrator or Mortar. Some of these, like Electrified, are also considered Missile (or Melee) but not all.
Yes. The limitations of the affix is whether it is a Melee type or Ranged. Like Resistances it is just sub-categories that depends on the actual hit.
However your Toughness does not reflect this as a .5 of effect. In the calculation I believe it only regards it at a factor .3
So a +30% melee will only grant around 10% increase in Toughness