Last, H2O below skimmers only or skimmers PLUS wall returns?

Kirsten, the amt to drain is up to you. If you have 'flooding' problems by the pool area, it's best to keep the water higher. If you can reasonably expect a few feet of rain/ melted snow (10" of snow ~= 1" of water), and your cover allows water to pass through it, you'll probably want to drain a little more out at closing, ie - to below the returns. If you are using a 'shop-vac' on 'blow', the lines will be easier to clear if the water is below them. In short, the amount of water to drain is dependent upon your particular pool (which is why making an all encompassing 'sticky' for IG pools is so hard - though Al did a good job of it- it would take a pamphlet at least to cover all the different types of filters, pools, covers and local conditions (weather, drainage, etc)) Go with the stickied info and, as you have, ask pertanent questions when your situation differs.