1. Well if they aren't moving they might be asleep. I can usually tell if my snake WAS asleep, cause I open the tub and they kinda freak out a bit.
2. 10-15% of the snakes weight is a good way to measure how much you should feed the snake. Hatchlings can eat every 5 days, juveniles ever 7, and adults every 7-10 days.
3. Daytime roaming, not using hides, trying to escape, not eating. You can't really tell by handling the snake, only by observing its day to day habits.