Lots of excellent questions, so I'll go one by one.
1.) I was out there right when you left 3 ish. I wish I had come a tad earlier, but I was bike riding for 20 miles.
2.) On a ESE or SE (which it was) you almost can't feel the wind at all yet about 10 yards above your head it could be blowing 15 knots.
3.) I judge conditions like others do around the lake....experience....experience....experience. It took a lot of skunked session before I got it right. Yesterday for example we have isolated SW T-storms. This sets up a classic E or ESE wind to fill the void to the SW from the storms. I use this meter.
http://www.glerl.noaa.gov/metdata/chi/prev3.html When I go ANYWHERE on the lake. I use it for Wolf, Waukegan, Miller, Montrose, and sometimes St Joe. It's isolated and off-shore and therefore damn accurate. Now on a North wind Montrose is a no brainier; it'll blow . On any kind of East wind is where it gets tricky. In the dead of summer it can say 20knts on the meters and yet we'll barely get 2-5 knots on shore. This is because of either hot water or the land mass heating up. Today's cool water and SW storms gave me the go ahead to give it a shot. I think all this and MUCH more would be easier in person then typing so maybe at the beach bar "The Dock" or sometime when we both showup for a session....just remind me and I'll spill my guts on my experiences.
4.) Beach crowd...ohhh the beach crowd. All I do is stay the F*$# away from them. Meaning pump up, launch, and get in the water ASAP. Montrose winds are very steady as long as they don't go more west then NW. Dogs off leash aren't too much of a problem, just shoe them away if they are curious about your kite and pet them if they come up to you
kindly, so they know we are friendly. I agree that it gets more difficult with people, but only in the dead of summer do I get a little worried, by the amount of space we get (signs here could be key)
Like I posted yesteday I was on a 12m and a 129cm board doing pretty good until around 6 where it died off. Jumping, kitelooping, deadman-ing, the whole bit all on REAL glass, not wavy BS people call glass. Really gorgeous day at the beach. Only experienced riders though as going downwind is going to be a problem.
4/3 suit IN MARCH!!!! CRAZY, but I love it!