Coolant level cold, with the bike level, should be at the MIN mark. Anything over that will probably puke out when hot.
I've run stock coolant, straight water mixed with Red Line Water Wetter, and currently Engine Ice. Based on observed temps via the Scangauge, nothing really has any significant effect on operating temperature. The thermostat opens around 190.
On my bike, it runs at around 191-195 at steady cruising speeds in ambient temperatures under 85. As the ambient temperature rises so does the coolant temperature. At 115+ I've seen coolant temperatures up to 210 cruising at 65 MPH.