First off I have had my RB26 motor for 6 weeks and have yet to get a part for it here in the US. I need simple re build parts (bearings, gasket set, oil pump, water pump etc.) and have yet to get any of them. Thier are several people/ shops that claim they have the stuff, or can get it, but most of them are full of it...
I'm waiting on all these parts right now from a guy in New Zeland (GTR Shop), since he's the only one I've been in contact with that can actually say he ordered the stuff for me...
You will have a heck of a time finding anything for these motors here... and thats just for starters. You will need a RB25det trans, the Z32 trans is not a direct swap. Then their is the oil pan, among other things..
The turbo manifold is two seperate three bank pieces, that are exactly the same. I could not notice any difference in the manifolds or the turbos on my motor. I belive they both are the same spec, and operate at the same time equally...
I have ditched the whole factory intake system, and the whole exhuast side of the motor in favor of a single custom plenum and twin GTr turbos on a stainless header that a member here is making up for me (SpeedshopThagard.com) and his name is James Thagard (240z Turbo).
Their are a couple guys on this board that have completed the RB26 swap into their Z's, so maybe one of them will add something to this for you.
This is just my opinion on your questions...
good luck
joel