I made the kerf cuts with my band saw. I did fold a piece of sandpaper in the middle to sand a little, (very little) but I don't think it is that crucial. A band saw makes a pretty clean cut and many people like to rough the surface up a little with a toothing plane before they glue anyway. I think you could use any profile you want midlimb without any ill effects.
I am quite sure the steam isn't essential for larger radius curves, but I think it was beneficial for these small ones. It takes a lot of force to bend into tight curves. I think without steaming it would have forced all of the glue out of the joint when it was bent which would be fatal to the bow.
I plan to make another one of these, only slightly longer for a hunting bow. It will be either straight or have a slight reflexed profile. I will cut several kerfs and steam it before I glue the recurves.