A: It is designed to work either way. I find it easier to place it on its side, as you won't have to worry about it falling over. The length depends on how far out you pull the adjustable tube, which is based on the amount of cigars you are humidifying. Closed the tube measures 3.75" and fully expanded it measures 5.25".
A: When you extend the tube, you can see the slots where the crystals are exposed. To refill, either slowly pour distilled water through those cracks or submerge in distilled water for about 15 minutes.