I was wondering that as well.
But for part B, maybe it doesn't really matter? I mean, say you consumed 500 extra calories that were converted into fat at noon. If you had the 500 extra calories of enegry waiting to be stored, at 10am, and worked out burning 500 cals, you shouldnt be storing any fat.
But what if noon comes and goes, you store the 500cal, and then work off 500cals at 4pm? If you didn't have any other energy immediatly available, wouldnt you burn that same 500?