Mark, I'm glad to see you here. Yes this is the right place to get the best feedback on all your questions. Someone here has done anything you can think of!
It looks like an ambitious project, and I am happy for you! I do not have any experience preparing a room, much less a new building or addition for trains. All my layouts after I left my parents' home have been in already completed spare rooms. (The teenaged layout was in a dark, dirty basement in a 1888 house.)
With so much space you won't have the issue of getting the most layout out of a small space. I see you also have planned many shelves for engines and rolling stock. I'll leave off for now with another statement I'm glad you are here. I'll look forward to seeing what is suggested and how your building plan comes together.
