Unlike virtually every computer system in the world which uses a variant of ASCII, IBM mainframes and midrange systems such as the AS/400 tend to use a wholly incompatible character set primarily designed for ease of use on punched cards. (For an excellent page on punched cards, see Doug Jones's Punched Card Codes).
There are a few Keurig K-cups that DO contain calories. They fall under two categories. Brew Over Ice teas and coffees (except Twinings) and Cafe Escapes. Keurig has kept those around 60 calories each. When in doubt consider the consistency of the coffee. If it is creamy- it contains calories and most likely sugar. If it is a simple black coffee, calories are not an issue.
I have the same Keurig and yes, the coffee is stronger in the small cup. The more water than runs through the k-cup, the weaker it becomes. I find the largest size is still strong enough. In fact, I sometimes reuse the k-cup and run the smallest size on the second cup.