I know this doesn't matter in any real sense but I'm wondering: if I were to acquire a blue Boff and have that Boff teach one of my well-trained, starting Boffs would my white Boff change color to match the blue skill that was taught?
Go ahead and have four regular crew that will be your primary and will carry most of your space skills. As you level up, you'll get more options to add more Boffs. You can make these your uncommon and rare Boffs and then cycle them out as you need them. The bonuses are all ground based anyway, at least that I've seen anyway.