well think about it, the ride height determines the usable stroke of the shock, not whether they are captive or not when you jack the car up. Having springs that are the same height, with one set being captive and the others not captive, you will not find a difference in the wear rate of the shock between the two IMO.

Even resting on the bumpstops, as long as you arent using tiny or non-existant bumpstops and therefore bottoming the things they will last a very, very long time (longer than you will have the car i bet!)

As long as you arent bottoming the Koni's they will be fine. Mine were for 18 months on non-captive springs before i sold them.

Not captive is illegal, yes...but perfectely safe as long as you dont start launching the car off speed humps to see how much air you can get

(i am assuming that the springs become captive soon after you start dropping it off the hoist though, if they become captive an inch higher than your ride height its a different story!!)