Both good choices, moto sounds great.
Calf - stiffer, heavier, tougher, probably not what you want.
Lamb - soft and light, very nice
Goat - lighter? than lamb, but tougher and has much more texture
If only one TOJ, general consensus is lamb.
Whiskey! Not sure on availability. Another great option is brown goat (super dark, almost black) if you choose goat.
In regards to the CWU, Drew has expressed a strong preference for them only in black, but I believe a few brown ones exist.
There have been some modifications allowed in the past on case by case basis. You would have to email them directly for a real answer.
Would email TOJ but I figure I'd get more direct info here.
All leathers are fully MTM, adjust away. You should email.