These bikes do get very hot at idle and the fan kicks in right around the top edge of the green, but they usually come way down once your moving. The drain valve should be in the off or closed position. It should only be in open position when draining or filling the cooling system.
Mother's or McQuires headlight restore works amazingly well to bring the windshield back to like new condition.
With regards to the speedometer accuracy, with great patience and a gentle touch, it can be adjusted. You need to remove the speedometer head from the cluster and gain access to the inside of the speedo head. Spinning magnets move the needle up the scale and a fine spring from the needle to a fixed tab returns it to zero. Spring tension affects accuracy by how strongly it resists or counters the magnetic pull of the spinning magnet. This tab can be bent ever so slightly to increase or decrease the tension on the spring to either increase or decrease this counter force which in turn affects the speed indicated by the needle. This can be a very finicky adjustment and is a total trial and error process. You may get lucky on the first shot or you may have to make several attempts. If the speedometer is running fast (which most do) you want to increase the tension.