All you really need to know is that a floating bridge works by balancing the tension of the strings against the springs. If you get to where you're close to being in tune and the bridge is angled upwards, it means you need to screw the spring claw into the guitar body further, thus pulling the strings. Rinse and repeat until the bridge is level. In these posts, you never mention the spring claw, so I assume this is the part you're missing. If you change tunings and/or string gauge, you're effectively changing the string tension, so you have to compensate by adjusting the spring tension too.