1. yes 2. yes 3. maybe (where are you filling your balloon - at the top or at the bottom?) Perhaps the biggest thing you're missing is that you are looking at a moment in time when 9 of your 10 balloons are already full, and ignoring how they got that way. Yes, at such a moment in time, you have more energy in your system than you are actively putting in. But you already spent that energy filling your balloons and/or getting them down to the bottom of your device. If you count the original energy spent 'priming' your device, you will always be in the negative.