I can't comment on shelf life, but I ordered the 250ml bottles a year or two ago for my Nomad. I only have one Rohloff to worry about and I expect to use it over more than a two year span.
Thorn has a good video on their website on oil changes.
I use 15ml of lube oil, not 25 in an oil change. I think that is the current consensus.
I re-use the screw, but I reapply blue Loctite to the screw each time I do an oil change. Dave in the shop has mentioned the possibility of dissimilar metal corrosion on the screw which encouraged me to consider the importance of a thread locker compound on the screw.
The complete oil change kit is needed to obtain the syringe, the plastic tubing with threaded adapter. And I think it has one spare screw.
I have a Nomad, not Raven. Thus, I can't comment on other spares you may want to have for the shifting cable setup. I think the Raven has some form of internal cable that you might want to ask SJS if you should have a spare or not. I think the other gear cables can be replaced with standard Shimano or Campy type road cables.
If you bought a leather saddle or two, a tin of Brooks Proofide may be a good thing to add to the order.