50/50 is recommended so run that.
Water.
Coolant I believe.
Always use antifreeze. Water does not have any water pump lubricants or anti corrosion properties, antifreeze coolant does.
no, sodium is sometimes used as a primary loop coolant as it carries heat better than water.
you should use coolant, therefore your bike will run cooler, the lower the engine temperature the better
Depends on the type of coolant and the main ingredient(s) other than water.
50/50 water.antifreeze.
Rapid Cooling can be achieved. water is a better conductor of heat, than air. Compact in Design, than that of an Air Cooled one. No need for large fins. Water is cheap. Water has to be mixed with coolant alcohol, to prevent freezing and stop corrosion.
The criterion "better" is not well defined. A coolant can cool faster, or to a lower temperature, or be more affordable or less toxic than another coolant, or more environmentally friendly. Freon is better than ammonia by some criteria, and worse by others (it is less toxic, but more environmentally harmful). Liquid nitrogen cools things faster and to a lower temperature than ice does, but you might not want to put it in your drink (which would immediately freeze and become undrinkable). Water frozen into ice is a perfect coolant for some purposes, such as keeping my glass of ice tea cold. I would use no other coolant for that purpose.
Because it has a lower freezing point than water. It can be cooled to below zero Celsius and remain in liquid form - making it a more effective coolant than plain water.
The boiling point of the mixture is higher than the boiling point of pure water; this slows down the evaporation of the coolant.
No, but it will cause other problems. Water is actually the best possible coolant, better than the normal 50-50 concentration of water and coolant. Here's the problem (or several actually). 1. Water alone doesn't contain any rust or scale inhibitors. Coolant does and will help prevent clogging and deterioration of the system. 2. Water will freeze at 32 degrees F expanding and possibly cracking radiator tubes and in extreme cases even engine blocks. Coolant isn't expensive so rather than risk damage it's best to follow car manufacturer recommendations for the type and amount to use. Add distilled water to the coolant then forget about it for another year or two. Cheers