Smiley Badge effect and implications

In Bravely Default, one of the accessories you can buy (unlocked via Norende reconstruction) is the Smiley Badge. The item states that it's effect is:

A friendly badge that freezes your aggro level.

This leads me to a few questions then:

1. What is the 'default' aggro level of a character? By wearing this badge will you never or only rarely be targeted?
2. If you wear the badge, and then use the pirate taunt skill or the ninja's detaunt skill, does it negate the effects? Or will your threat go up/down and then lock in at the new level?
3. Are there true threat mechanics in Bravely Default? I know there's a taunt skill (Pirate) and a threat deduction (Ninja) but do you earn aggro by attacking/healing? Does this mean that the more damage a character does, the more likely they'll be targeted? How does the threat system work?