I'm excited about the rack too. I'm going to get a nitto ZL decaleur to support a bag from above. This should be compatible with the existing stem.
I'm not sure what provisions if any the frame has for internal dynamo routing, but I'd like to use a front dynamo hub. I know the D1/D2 variations of the frame (red) had a rear bottle dynamo along with canti brakes.
I'll ID the saddle when I get the bike and let you know what it is, I'll likely switch to a leather Gilles Berthoud.