Chain is standard. Eyelets won't be a problem, as you describe. Yes, I'm pretty sure you can find a square-taper BB spindle that'll work in the original Raleigh cups. But in all likelihood the existing crank is fine. Changing to a cotterless one will save you a small amount of weight, but not enough, in my opinion, to be worth it. The original Raleigh crank is nearly indestructible, attractive, and... well, it's original. Can't be beat!