Yep reading lots is your friend. Really sounds like you have no real set idea in your head of what you really want from the car. And research this forum is what you need to do to work out what you want out of it and how far you want to go. As not having a rough idea what you want out of it can end up very costly. For example you said your turbo choice is a 3076r or t04z, two completely different turbos which does not really make sense,lol. A 3076r will come close to 360rwkw on e85 setup correctly. So not far from your goal of 400kw. I wouldnt bother with a t04z as there a dated turbo now and will be rather laggy on a rb25. I strongly consider a gtx3071r, very good all-round turbo for a rb25 on e85. 340rwkw with awesome response. I could go on and on but I think you get the idea.
Cheers Josh