Well, maybe you'll be happy to hear that I think I've run out of questions. I mean I covered the basics like gearing etc. The reason for the steel frame is some comments from a cyclist on Youtube. Mechanical disc instead of hydraulic, well I'd rather go with something I can adjust on the side of the road. Anyway, there's a reason for the various parameters.
(I'm not against an aluminum frameset though due to the lack of rust and light weight.)