Attacker’s AC effect on pummeling attacks

On page 72 of the DMG under Pummel – Base Score to Hit, it says

Attacker’s AC, per point, with negative AC being treated as positive by type* +1% …

* Magical protections such as rings … do not count as AC, so ignore them; encumbrance = AC 10

I take this to mean if the attacker is unarmored, they have a 10% bonus to their attack roll. Plate Mail gives a 3% bonus. Cool, got it!

My questions are as follows:

  1. If I have a dexterity bonus of -2 to my AC, does that lower my chances to hit by 2%?
  2. What is "positive by type"? Does an AC of -1 from enchanted Plate Mail +4 just give the Plate Mail bonus of 3%?
  3. Do magical bonuses from armor or shield affect this calculation – they aren’t rings or bracers?
  4. Does the attacker being encumbered (by how much?) give a 10% bonus regardless of what armor they are wearing?
  5. Why didn’t Gary just hire an editor (You don’t have to answer this one 😛 )