How to grease a pan without shortening or butter
Vegetable oil will be fine - that's what's in commercial nonstick spray oils anyway.

A pyrex oven safe glass pan is a baking pan. The baking time might be slightly different than with a metal pan, but it will work perfectly fine. Just make sure it's the same size pan the recipe called for, or scale the recipe to match the area - if you change the thickness, the results are going to change.

The dutch oven (uncovered) would also work, though it will take a lot longer to heat up, so it will probably affect the baking time substantially, and you may have to be careful not to overcook the top.