[vl]

Re: orbital assembly. L1 point is bad in every respect. If most materials come from Moon, then the best assembly point is low Moon orbit (as benefit you get a boot to your launch speed to escape Earth gravity), if most material comes from Earth, then best assembly point is low Earth orbit. Hauling all material to L1 is going to be more expensive in either case (unless the ratio of materials is very exact, which is unlikely).

Re: spin. I still claim that the best design is to rotate entire living module as one. Most of the activity is going to be on the outer shell. Warehouses, etc will be in the lower gravity inside. No moving parts.

The only question is what to do with fuel and retro engines. Rotate them as well? Fuel tanks need to be stronger. Do not rotate? Then maybe living module can undock for the flight and rotate separately.