[Dust]

water/meth can cool the air to a lower temperature than the IC can, you have that right, but something to consider is that a cooler than ambient IC is a good thing. Air is always flowing through the IC, so air will always be cooled or heated by the IC.

Whether or not to run an IC, in my eyes is a matter of speed. If you're normal speeds will be low, and alot of stop and go, an IC won't be as beneficial as a highway toy. Water/meth can start cooling as soon as you hit turn-on, not as soon as you have had ample cool air running across the IC to remove heat.

For location, I would look at pre-turbo, and post turbo, in a straight pipe for the mix to get mixed without an IC. the pre-turbo will cool the pressurization, and right after the turbo will cool the air further. I don't see a reason to go direct port unless you have a horrible intake manifold.