I use coconut oil for caps too. I decarb the weed first and then heat it in the oil and strain. I have never tried to do any storage except in the refrigerator/freezer but coconut oil is supposed to have antibacterial properties so it may be fine. We store the straight oil un-refridgerated and it doesn't go bad. I do know that canna-butter does go moldy even in the fridge after enough time though.
Yes, for storage, i would like to make a bunch and can it up in jelly jars to keep it fresh, i am only adding a spoonfull to my coffee and with kids in the house(teenagers) i would rather not have a half gallon of the stuff available in the fridge