Agility and AC; question(s)

[Scavrefamn]

I am not well versed in how AC works.

I know some people studied it and have extensive knowledge, so I will ask rather than incorrectly assume, here are my questions:


Is it worth it to look for agility the AC benefit?
How much agility = 1 AC?(7?)
Does agility "really" help with avoidance?
Does this agility AC work better/worse/the same as armor/shield AC?


Thanks in advance.