Congrats, these cars are an absolute blast with boost. For boost control you can go with the HKS EVC or I also like the AEM TruBoost. Both are an all inclusive unit that can store multiple maps. The HKS is a bit more involved and the AEM is fairly straight forward. They both have some failsafes in place. You can adjust both boost onset and wastegate duty cycle with either option.
Go ahead and do the oil cooler with the build if you can. Even during the cold months when you are having some fun you can still watch the oil temp creep up when its cooling two turbos and the engine. I would also swap in a set of GT-R plugs instead of gapping down the OEM plug. The OE plug is a .44" gap. You can only knock down the gap a maximum of .08" (per NGK). The GT-R plug comes out the box with a .32" gap which is much more appropriate for boost.
What turbos did you get with your kit? Good luck with the build! Its a hell of an install with the engine in the car, haha.
Thanks,
Alex Goodwin
AlexG@motionlabtuning.com