the freezing up, could just be somethin like sticking under the magneto, maybe bad main bearings, maybe was quite dry internally, lots of things. if it happens again just be sure to really look at it and you'll have an easier time placing the problem
as for idle, i let the back wheel spin no more than i can stop by grabbing it with my hand. this is what I say. more often in reality, i just set it to where it works. do as i say or as i do, either way you're solid.