Two notable details shown here include the cut-away dropouts and the angled plate supporting the ISO disk mounts. The dropout cut away is to lighten up the area. I like to use 1/4" thick chromoly for dropouts but in this situation I did not need the full strength of a solid slab so I cut them up a bit. The disk mount is supported by an angled plate that is thicker than the tube wall for strength, The angle puts the mount in the exact location needed.
When I have a choice for disk brakes I choose Avid BBDB 7's. They are powerful, simple and easy to adjust.