Notes on the spool. In general you will get more breakage running a spool if you hit stuff. In the Evo4 the drive cups break easiest and I now have aluminum ones and they are holding up well. It transfers so much force to the driveshaft, I even bent my Jurgen lightweight shaft. I run the Speedtech spool and it is a single piece of machined steel and looks like it will last forever. I think I would rather have the steel spool than the flex generated from the long slots in the stock plastic diff halves.
The Evo4 hubs from Tamiya are 1 degree in plastic or aluminum. I am using the ones from Square and they are indeed 1.5 degrees.
loosenut: Make sure you use Loctite 242 on the screws for the crown gears that go on the front and rear shafts. Otherwise, they will become loose and cause problems eventually. Your parts list looks pretty good and you will want to add 950 bearings to the list because they do wear out quickly.