I think your plan is already a lot better than I could come up with. I am not much of a track planner, others here are much much better. I have been fiddling with an addition to my layout for about 1.5 years now and I don't think I am any closer than when I started. I think you have a much better idea of what you want as well. I also struggle with that part.
Looks like you also have some friends willing to lend a hand near by. I think it's good just to have them stop by and offer suggestions too. I think the natural brick wall is kind of neat too. Might be neat if you could work that into the layout some how, it would be something different than most. Just a thought...
Anyway, I wish you luck and I will be following along.
