1) Correct - set the boat up (sails up, main NOT sheeted in) and use the main halyard to measure on the windward side. Use the jib halyard to adjust rake and wrap a small piece of duct tape around the jib halyard at the black band on the mast. Note that moving the jib tack up or down on the forestay adjuster will change the setting.
The reason you don't sheet the main in is to keep the CompTip from flexing.
The standard main halyard has black flecks about every inch, so you really don't even need a ruler to do this.
2) It does sound counter-intuitive, but it works. The reason is that you want less leech tension in light air, therefore you can carry more mast rake (and point higher) in the light stuff.
3) Short answer - yes. Depends on the waves. Short, steep chop - you want the power on all the time, so you don't feather in the gusts. You (or more appropriately, the crew) works the traveler. It also depends on the tactical situation. If I'm pinching to make the weather mark, I'll feather to gain distance to weather at the expense of boat speed. You need to be ready to crack the main a little bit when the gust passes to help bear off, though.
3a) It's on the calendar at this point. Megan will be back from camp, so I'll have my minimum weight crew again