I'm not a fan of slowing down that much. I think a click or two can be beneficial, but if you slow down too much, it's basically a different pass. And, since skiing is based on rhythm and timing, it doesn't make that much sense to me. But, think of back in the day when people were hand driving and you'd get a 16.25 or a 15.98 and how different it felt.
I've never messed around with half loops, but as you said, you can run 36.5 all day long, and 38 is tough, so also doesn't seem best. There are a ton of different angles and the pull coming in at different times.
I have actually moved buoys in. We had a floating course in college, so we had two sets of hooks. We would keep them on the record setting, but did move them in to tolerance for Class C for collegiate tournaments. It made a world of difference. Not like I was running an extra pass or anything, but just running what I could pretty easily.
Weaving is only beneficial if you have someone who knows how/when to weave. If you aren't picking the skier up out of the turn, or whipping them in to the buoy, definitely not helpful. But done right it can make a world of difference. And, honestly can just help the the monkey off your back. Once you've run a pass and know it can be done, you do it. I have weaved many a skiers through their first pass, and two passes later, straight as an arrow, and they are still running it.