David Hawkins 250's page

Let's say PCs are setting up an ambush in a 10' wide corridor. The bad things are 40 feet away and the PCs are stacked up behind each other.

If a PC in the 2nd row makes a ranged attack, that is still +4 AC to the defender for cover? Are there any rules to cover that situation, or is it always just blanked +4 AC.

Also, what if the PCs in the front row kneel. Is there a rule to handle that, or as GM is it something you can houserule and make it only +2?

I am running a game where the PCs are in a tunnel and 10 feet above them are undead. If the undead decided to drop down through a hole in the roof, how does that work?

Falling damage says by jumping instead of falling they take non-lethal damage. Undead says they take no non-lethal damage.

Does this mean undead can jump down 10 feet at will?