I don't know that I would worry about it. Depends to some extent whether you think this will be a showstopper, or a prototype. While I am suffering along learning the hot arts, I could whip out a wood epoxy anything, perfect first time. 30 years at it tends to do that for you. I'm traditional about BBs, but use whatever makes you happy, doesn't sound as though you have your own view on the matter so why worry about it. Your head tube will be standards, and if you cut it right you can put any headset you want in there. CK is the custom bike builder's favorite, sorta how you can tell it is a custom. That seems unlikely to be a problem with a wood frame... But it is a reuseable part so I buy the best I can get, and can keep shifting the frame forward as new ones come along.
I don't know about the part you are after for the deraileur, but the part sold to braze on is relatively simple, and could easily be made with whatever tail on it with simple tools. Or welded to whateve extention. If you can't find what you need directly, pick up the braze on part for pennies, and go from there.