No such thing as polars I'm afraid - at least none I've found.

Only comment I can offer is in the 2nd question.

Its faster to ease in the puffs. However you have to consider you and your crew's ability to do that for a full day of sailing. Truth is some combination of easing/feathering which is very dependent on a whole host of variables. However, as a general rule, assuming you're overpowered, the more you ease the faster. However, don't ease so much that you're footing too much.

Also, don't forget the cunningham. It's an incredibly effective de-powering tool. I've been told the goal is to adjust the cunningham such that your sheet adjustments are only inches (not feet) at a time. If there are lots of variations in wind strength, it might require 3-4 cunningham adjustments on an upwind leg.