Just my opinion but I'd go with 700c wheels for someone your size. 26" or 650c is great for small riders but small you ain't.
For the brakes, I've never used the Tektro calipers but considering you are fillet brazing the entire frame I'm not sure what your hesitancy over cantilevers is based on - I'd just go ahead with them.
Many older road bikes used above the bottom bracket cable routing. These used exposed wire not full length cabling.
Bending forks blades is not that hard. There are templates out on the internet so you can make a mandrel of wood. I've used one and had no real issue. That said, there are several good straight blade fork crowns on the market. 1" steel steerer is tried and true. No worries although 1-1/8" headsets tend to be tougher which is a good thing if you are planning on riding off road a lot.