To prepare for the freezer, let the calzones cool completely. Wrap individually in foil. Place in a resealable freezer plastic bag and label. To reheat, bake in a 300°F oven until thoroughly heated.
You can add any filling you want to a calzone. Use whatever leftovers you have to make a filling.
Calzones are perfect for lunch boxes. They travel very well in a lunch bag with an ice pack to keep them food safe.