1. Don't bother with a t25, your motor will end up out flowing the turbo. Also, the t25 is VERY small. It will create a great amount of heat under boost. Go with a hybrid t3/t4b series.
2. Standard bore will do. If your going that far into the motor there is a LOT more stuff you'll want to upgrade.
3. Go with an ITR tranny, they've got standard LSD and all that fun stuff along with super short gears. GSR or B16a tranny will do. The LS is fine if you don't have the money.
4. I wasn't sure how much pressure you were talking about here, Im assuming 14psi and 7psi those are rounded-down numbers of .5 bar and 1 bar. [ 1 bar = ~250whp | .5 bar = ~200whp ] Your mileage may vary.
5.t3/t4 60-1 will make upwards of 400whp
6. Block work...? You don't have to get any done if you don't want to. Like John has said before, he's gotten something like 275whp out of a stock LS block.
7. You don't need any head work. I would however suggest a turbo cam, springs, retainers, and over sized valves. Keep them all from the same company if possible.
8. FUEL. For god sakes don't run lean. 440 RC injectors, and Hondata should be your absolute MAIN concern. I can't stress that enough.

I hope ive been of assistance. If anyone wishes to add stuff, or If im wrong somewhere, don't flame just add your corrections.