To be quite honest, I do not know how well a single TB injector will handle boost. I do not even know the spray of the E16i's single injector; I know it is a good deal as compared to a MPFI setup. It might handle boost just as well as a regular MPFI setup mated with a smaller turbo. As for turning down the fuel pressure, I wouldn't do it since you only have one injector. If anything, you'll run lean, so you'll want to increase the pressure; at least that is what I discovered when running a K03 with only an adjustable fuel pressure regulator (whited the spark plugs nicely).
I figured you knew how to run oil lines to a turbo, but one does have the check
. You could always use an E15ET oil pan, but like you said, have fun getting your hands on one of those.
In regards to the E15ET manifold and ECU, you'd probably need all the sensors (MAF, air temperature sensor, IACV, etc.) Your coolant temp sensors will most likely be the same, as will the cam position sensor. But, with the E15ET manifold, you can run larger displacement injectors (not sure if top-feed or side-feed; I'd bet side-feed) and a better MAF sensor. That makes tuning much easier if you care about not destroying the engine. Otherwise, just run balls out and see what tweaks you can do to keep it running.