In cases 1 and 2, the effect providing concealment is on the person, not the illusion of the person. So in my opinion, neither of them would impose any miss chance at all to someone trying to hit the illusion.
So I'd handle it like this:
1) Roll to see if they randomly hit the actual person with Mirror Image, or one of the illusions.
2a) If they hit an illusion, and they roll high enough to hit its AC, then it's popped.
2b) If they roll to hit the person, then they roll the miss chance of the concealment or whatever.
In the case of Darkness, the Illusions are actually also affected by the Darkness. So they'd get the benefit of concealment as well.
As far as RAW to back this up, you don't need anything other than to look at what each of the effects is targeting. Blur, Displacment, and the Swiftblade ability all affect the caster, not illusions of the caster.