I think you are definitely starting on the right end. I can see where starting elsewhere might just create a problem or tow later on. Probably would with me as well. I'm betting Dave's plan will be pretty accurate, he's really good with those track plan programs and layout design.
I think piano movers would be a good idea too, if budget ever permits. Someone inexperienced could get hurt trying to lift/move that thing! Hopefully your work will pick up to where you can be comfortable until full retirement. Good luck with all of it, and all the extras you are doing for the old folks and the other properties. To me, that sounds like full time work!