If I start the wrong hpf morning/evening cal set, what do I do?

A cntrl-C, executed in the scripts window, can be used to stop the currently running cal script. As withh all HPF exposures, whever is happening at the time you issues the cntrl-C will have to finish. When the script has stopped you can then issue the correct script command.

There is a good discussion of this in a large docement covering HPF.