I'm making some changes to siege weapons and walls/gates. I have a few questions:

1.- How do I make certain structures “non-eligible target” for certain siege weapons?

2.- How do I strengthen gates? In descr_walls, for example, there is an entry for short wooden walls:

gate short_wooden
{
full_health 100

and later another:

gateway
{
full_health 10

What is the difference and which should I strengthen to make the gates stronger?

3.- Where do I edit rams to tweak their anti-structure strength?