Like i said if you have the brackets the IC will bolt straight up. It'll line up with the turbo perfect and the throttle body but you'll need an adaptor for the trottle bod or get a GrpA one.
As for the pump and lines, you have all the bolt holes etc in place (the 184 does not) so it's just a matter of bolting it all up...should be easy if a little time consuming.
as for the eternal question a/a or a/w? there are endless debates about this everywhere on the web. I said that for a street car there are some adavntages but the ultimate is a big FMIC. I kept the a/w because i knew i could make it work well and it's in keeping with the GrpA...i didn't want to butcher a GrpA too much.
20psi would be pushing a 185 a/w but with WI no probs at all. And yes a bigger turbo *generally* is more efficient at a higher boost than a smaller factory turbo so for the same boost level there's greater air flow and less heat.