Motor mounts many options, either place the motor in an undesireable position by using the 200ZR mounts (avail from Nissan), or go Brad's Mounts, Infinity Machining Mounts, or those Aussie Mounts
Part numbers are all throughout the RB Forum and are available from http://www.nismoparts.com for $183 Shipped (Pan, Pickup, and O-Ring)
Trans mount will be fabbed (there have been many ways on this forum, 2 that i've seen). Driveshaft either cut and welded or a nice new one that's custom length.
Stock manifold, depends on if you plan on a RB20/25 or a RB26. RB26's you wont really need a new manifold. The RB20/25 wont need one either, but I would highly recommend that or get a custom fabbed one like the other guys on here. Too much piping if you ask me with the stock ones.
(My friend did a RB20DET with the stock manifold, you can see about as much piping in there as the Alaska Pipeline)
As for me, i'm still working on my RB25DET. GOOD LUCK!