Character can get to 0 hp is unconscious. Character dies at -10 hp. Character loses one hp per round unless healing applied.
Monsters are not restricted to the Monster Manual HD. For instance, a 6th level Orc Fighter is possible. Monsters may have better armor than in the book as well or have different abilities. Do not underestimate their intelligence.
Donning – It is assumed when not awake, armor is not worn. The more complex the armor, the longer it takes to get on. Hide, leather, chainmail armor; 1 rnd. Scale mail; 2 rnds. Platemail; 3 rnds.
Existence- The highest level of armor in viking nations is chainmail. The highest level of armor in Roman areas is Scale mail. Plate mail is a very recent addition and only the richest mercenaries wear it. There is no plate armor.
Discarding – If a PC fell in water, it is assumed they are hacking the straps to the armor. Once again, the more involved the armor, the harder it is to take off. Once the straps have been hacked, it will need to go to an armorer.