The fridge is small. I don't think a gallon would fit. A half would fit on its side, you could probably fit two in there but then you wouldn't have much room for anything else.
They do supply a few kcups. If I remember it was a light roast, dark roast, decaf and tea. There are a few little packets with sugar and stirrers and stuff. I am not sure if they will replace it or not.....right now there is not daily housekeeping so you have to text them to replace things in the room and they drop off. They will bring more cups though, as we had requested that.
We are cereal in the morning type people. However, for our last 2 Universal trips what we have found that works great are those oatmeal cups. I run the hot water through the Keurig to make each oatmeal cup and then we eat with an applesauce pouch for breakfast. I bring from home a ziploc full of plastic spoons, little creamers, and our favorite kcups for coffee. You could also use the packets, but I like the cups because they are a bit more "deluxe" and not something I would normally buy at home, so it is a treat for my kids. We always take a food suitcase with us when we travel (we fly southwest) so it is easy stuff to pack! We usually do a quick stop at the Walgreens down the street for water (bottles for the parks, gallon to use with the Keurig) and gatorades, but we bring most of our food with so we don't need to go to a grocery store.