I find that mine is a little hard to turn over at first, the starter can't cope with it until it's loosened up. I find that if I prime it and get it loosened up then it's too wet to start and I have to flush the fuel out by removing the plug and spinning it.

I've put a Zinger 12x6 on mine, it's the size OS recommend for break in.

The last time I tried to start it, I must've spent a half hour or so on it with no success. I gave up and went for a coffee. When I came back it started first time! Talk about tempermental...

As far as mixture is concerned, I just checked it and the needle is open about 2 1/4 turns. I haven't noticed any behaviour changes during flight like you mention, but then I'm only plodding around with a trainer at less than 1/2 throttle.

Lastly, what is meant by backwards flipping? I heard this on here a few times, mostly in connection to 4 strokes...maybe the engine will respond to that.....