Damage Immunity (Minimum) - what is minimum

With the change to melee damage going from 1 > 2. What is considered to be the minimum damage increment in DR? (This sounds like a stupid question, but I couldn’t find it anywhere in the book).

Do zombies take 2 damage from ranged weapons or 1?

The threat books provide more details.

Semi related question

Does ranged immunity apply to ranged weapons only, or also thrown and exotic?

Thrown and Exotic are Ranged Attacks as well.