Are the brakes front and back on a 280Z the same as a 280ZX(rotors, drums, etc.)?. Which ones are and which ones aren't?

In a word, no.

The ZX has disc brakes all around, while the 280z had them only in front.

The calipers are different, even though blackdragon doesn't illustrate this in their catalog.

http://www.blackdragonauto.com/icatalog/z/0099.asp

The calipers I have on my ZX (stock) are item #5, not #4 as they say (and you have on your Z).

As for upgrading, I really can't help, other then to say search for "toyota 4x4 brake upgrade," as this is a common swap. FWIW