working the clear before its hard will tend to cloud the part your working on.
Someone will have to explain this one. I've buffed MANY a clear job some within 24hrs and NEVER had any clouding. It's possiable if it's not cured enough to sand (the balling up I mentioned earlier) but if you can sand it,you can buff it.
7",5/8" arbor is the most common. The MAIN thing is the RPM they run at.That's what you want to pay attention to.1700 is the MAX you want to buff with, you can use a faster one but you'll have to trigger it on & off to keep the speed down.