Some counterpoints:
1. More RPM with the same gearing makes you faster; more rpm = more better (at least till you can't afford to go higher)
2. The turbo doesn't really care about the temperature of the air going through it, but it will add heat on compression. The best way to get around this is with water injection right into the blades (literally having a nozzle a few MM away from the center of the compressor). You only need this if your turbo is maxed out on flow and you need a little bit more out of it (like for class limited racing). This will eventually destroy the compressor though, so not ideal for the street.
3. With air/water intercoolers there are pretty much 2 types: those that run ice boxes and no heat exchanger, and those that run exchangers and no ice boxes. If you run both, your ice water will pick up heat from the exchanger (because if the water is colder than ambient of course it will do that), limiting longevity of that ice batch.
4. I would run the WMI before the throttle body to give it more time to pick up heat from the air stream (if your goal is cooling only). This was my chemical intercooling setup:
You'll notice I put the WMI nozzles (2 of them) on 2" pipe and pretty far away from the throttle body. Any step up in pipe diameter is going to result in a slight and momentary pressure drop, which also reduces heat of the decompressed media slightly. This is why you want to spray as far back as safely possible.
Oh, and you won't need a larger throttle body till you start approaching somewhere around 600-800 WHP or so.
As for the larger washer reservoir,
@Shwa is correct. I had mine imported from Canada (via Edge Autosport) and it bolted right in. Found out the other day it actually holds *slightly* less than a gallon when filled to the brim. If you pair this with another 3qt/1gallon tank you can put that on the drivers side with the pump and run lines to join them without any real issues.
I'm not sure if your goal is to just be different; if that's the case, then disregard and go for it. If your goal is to make a bunch of free power efficiently, you'd gain a LOT more by simply adding ethanol to the fuel tank and getting tuned for that (like, not even joking here, ethanol does crazy shit for these engines), or by running a bigger turbo and gaining thermal and flow efficiency there.
Oh, and if you're interested in seeing how to properly set up an air/water intercooler (as far as intercooler and exchanger sizing goes), look no further than computer watercooling. The fin area on those is generally no larger than a quarter (and twice as tall), but the radiators are quite a bit larger. Then, you need to look at thermal loading (in watts TDP) that they can handle and if you're lucky, you can find information regarding radiator temps for that all important delta temp. It's all the same theory, but with a significantly larger thermal load being needed for cars.