The above answers sound good to me. One thing I will add is that it's important to make sure in flat areas, that your highpoly is truly flat. So that means enough loops and divisions that the surface does not get curved, otherwise your low poly bake will not be flat in turn.
5. any way to toggle between flat shaded and wireframe and map this to a hot key, I've found toggle shaded and wireframe but not flat lit and wireframe.
The "Flat" one is 722 and the "Nice" one is 1278. There will be exactly 10 in the scene which means the nice ones cost ~5000 more tris than the flat ones.