The exhaust ports on the 13B-REW are bigger than the earlier 13B's. You will need a custom manifild for the twins = big money.
You will not be able to operate the twins sequentially as indicated above unless you use a Haltech E11K as far as I know the E11K is the only EMS that will control the twins seguentially.
The 13B-REW will bolt up to a 2nd gen tranny, trust me, I know.
Like everyone said it is generally a PITA to turbo a N/A. I know 2 people that have sucessfully done it. One has a true n/a motor and runs very low boost (5 PSI) and from what he says the throttle response is awesome and it puts down decent power. (240RWHP is what I recall) I dont know a lot about his setup but I know it was not cheap.
The other Turbo N/A blew its engine. The owner took the opportunity to put lower compression Turbo rotors in when it was apart. His setup is pretty simple, hybrid t-04e, 720cc secondaries, s-afc, manual boost controler. He is running about 12 PSI and the car is pretty damn quick.
You might want to consider selling your N/A and looking for a TII. I think it will cost you less in the long run.