I agree with all your points, honestly. The biggest issue really is resource acquisition, definitely.

Y'know, now I'm wondering how exactly you'd defend such an operation, if required. After-all, such a massive structure would be an extremely high value target, both for capturing and defending.

Would you fortify the ringworld itself, or would you use dedicated defensive craft? Probably both, or one or the other, depending on what you're defending against, your tech level, and all sorts of other things.