No.
Yes. Just make modular pieces and you’ll be fine.
You should get better performance using Nanite over tessellation/displacement since you can enable Nanite on almost everything, plus Nanite has no perceivable detail loss at any distance.
Only downside really is that you can’t deform a Nanite enabled SM, but it shouldn’t be an issue if your structure is made up of modular pieces.
Right now you might have an overdraw problem with the Nanite enabled wood planks. Even then it’s still a better option.