2.) 37hp is barely enough to hold 70mph at 4000 feet up a hill against the Wyoming wind carrying a single 195lb rider without any baggage. I was using full throttle for much of the trip. It will run 75mph all day long in relative comfort on level ground.
I can't speak for the 4000 feet part, but at sea level it'll haul my 210 lb ass and another 40 lbs of stuff up a freeway hill at 70.
In general, I don't run it over 5000 RPM on the freeway (stock sprockets), which my GPS tells me is 69 MPH (and my speedo says is 76 or something).
3.) Riding a small bike on the freeway is nuts. I will not do it often if I have any other option. At least in the winter in Wyoming there isn't much traffic. Wind gusts often scooted me into the other lane. Did I say it was windy? It is often windy in Wyoming "because Nebraska sucks" though in this case it was because Colorado sucks since the wind was coming out of the north.
I really don't have any comparison, because the only thing I've ever ridden on the freeway is a KLR, and mine has a 2006 fairing. There was a day crossing the Bay Bridge that I couldn't lanesplit in slow-and-go traffic because I was getting blasted all over. Another day I crossed the Carquinez Bridge and the crosswind just about pushed the bike out from under me, I felt.
The behavior of the bike in a cross wind seems to be that it gets pushed sideways under me, but continues to track pretty well.
I think, though, I don't get exposed to the same level of wind that you do.
4.) 50 degrees is fine riding weather. I wasn't cold at all. I need at least four more inches on that windscreen, though.
Wind blast hits me basically at nose-height with the stock 2006 screen. Living in California, I don't get much freezing weather, but I can bundle up good enough that in the mid-30s, the only thing that gets cold is my fingers after an hour or so. Better gloves or warmers would fix that, I'm sure.
5.) Pulled off in Story, WY to take the back roads to Sheridan and fairly quickly had a flat on the rear tire. Darn. I haven't ordered the tire irons or center stand yet. Will trailer it home this afternoon and figure out a milk crate setup so I can get the wheel off.
Man, that's bad luck! I'm still waiting for my first flat 9000 miles in.
I use two auto jackstands to prop my bike up, based on the work of a guy I saw on the Internet. I cut vinyl tubing that I put on the frame to protect it, and put one jackstand under the right side frame, and then the other under the leftside frame. After I put on my big-azz skidplate that blocked the frame, I put the vinyl on the jackstand heads to provide a little more "stick" between the jackstands and the skidplate. I've taken the front end off and the rear end off with this setup. Seems stable enough.
Alternately, you can just put a stick under the frame/skidplate on the right side and prop it up. Not quite as stable, but it's not too bad if you lock the front brake on. This is what I have with me when I'm riding.
This guy built a cheap lift that I totally dig, but I haven't made one myself: http://www.nightrider.com/biketech/bikelift.htm