Do not mount the tank too high. The centerline should be level with or just a little higher than the spray bar in the carb. When refueling, (depending on your tank configuration) if any pressure tends to build that sends fuel to the carb, make sure that the throttle is all the way closed. This will slow down any siphoning into the carb.

Yes, engines tend to need a little more nitro in the cold months..... if it is so cold that they do not want to start or to idle right.

Best of luck!

Ernie