This is all great stuff.
I think I am in line on a lot of these things. I have trained serve more frequently, especially when the players are young because it gives you such a relative advantage in matches (looking at stats, it is not rare to see opponents with 0 Aces and 20+ double faults). If I can avoid double faults, I'm picking up 20-30 points a match. I've found that to be big in early rounds of tournaments (thus making sure you get more matches for the week).
I'm sure more questions or comments will follow.