Hey Null, sorry that the swim season's over for you

Your plan sounds good. For the skimmer, try removing the shop-vac hose for ~ 5 seconds once the water is just 'sputtering' out and then reapplying the air. This will let the water still clinging to the pipe puddle and it'll all shoot out at once. Do this a few times until all you get is a fine mist coming out, this will insure that you've gotten as much water out of the line as possible. Add the antifreeze and gizzmo (put a few wraps of teflon tape on the threads to make sure that the line stays water tight.

For the returns, it's a little easier, use the valve to switch from one line to the other while forcing the air through it, the water in the closed line will 'puddle' and then come out as a big gush when you reopen that line.

Have a good winter and I look forward to seeing you here next spring!