Goodman Games

I was looking for where in the rulebook it states the AC for each type of armor, but can't find it...I think I can infer from the bonuses listed in the Table on page 72 and the text on page 78 that if an unarmored person is AC 10 and a person wearing leather armor is AC 12, then it goes like this:

Padded: 11
Leather: 12
...
Full Plate: 18

Do I have this correct?

Right. Each type of armor lists what it adds to the AC total.

Agility Modifiers also influence AC, either up, down, or not at all.

There is a Birth Augur that can modify a character's AC, as well.