How do I calculate wattage of one single (1) T8 and ballast used to operate a vending machine, and how does the refrigeration affect the life of them both?

You don't calculate, you need to read the datasheet published by the manufacturer, or the label on the unit,it will provide the input watts. The high frequency of the solid at state components actually reduce the published watts of the lamp.

Different manufacturers will have different, close, but different loads due to differences in design, efficiency's and characteristics of the different components.

The T8 is a 1" tube and the wattage should be marked on the tube. Most are 30, 32, 40 etc. The ballast should also be marked as to the maximum wattage. Electronic ballasts use little electricity. There are efficiency factors on all tubes, they do not convert 100% so some energy is lost there. As far as refrigeration, if the fluorescent gets too cold it will have trouble starting as the mercury has difficulty vaporizing. Indoors this is not much of a problem but is outdoors. Why not go with a T8 LED tube? No ballast, very low consumption, much higher initial cost.