So for my extra large cupcakes this made about 18. I misread the recipe though and added 1 entire can of pumpkin, instead of 1 cup (oops!). I ended up adding more flour to make up for the extra wet ingredient. I also subbed whole wheat flour for the all purpose flour, and milk with a splash of white vinegar for the buttermilk.
Yes, I use baking cups. I use the If You Care brand which seem to be environmentally friendly (no chlorine is used in the process). I also toss them into the compost bin after use, although I don't actually know if that is an effective way to dispose of them (?).