First off, great weld! Looks really nice! Practice a LOT before attempting to weld your O-1, but other than that you're on the right track. I don't personally use the coat hanger trick as it takes precious time to conduct, what I'd suggest is to use it until you can recognize welding heat when you see it without the test. Forge welding is all about speed, accuracy, and just the right amount of force behind the blows. Tapping lightly is the key to it, which it seems you have learned "Is it better to heat the entire billet, and attempt to forge weld the entire length in a single heat, rather then attempt to do it in sections?" A single heat is best in nearly every circumstance, as it takes less time and fuel to perform a task. If it's possible to forge weld it in one shot, do it. Keep at it and you'll be there in no time!