2 of these things can be handled in a roundabout way by bvc.

Store credit can be handled by issuing a gift certificate.

For exchanges we have a custom status code basically "Waiting for Exchange Product". We create a new order with 2 line items for the same product, one with quantity 1 and one with quantity -1 which results in a zero balance order. Move the order to the custom status. When we receive the item to be exchanged, we change the status to a release to warehouse which allows the product to ship. Only the product with qty 1 is shipped as the lineitem with qty -1 is already considered "shipped" by the software ship the number remaining to ship for that lineitem is not >0.

Stored credit cards a db hack exists to kind of enable this depending on exactly what you are looking to do. However, I doubt the software will ever support it out of the box as new credit card compliance rules do not allow the storing of credit card numbers.