Hi Jeff,
The session in qListForm gets set when the item is saved or when the form is loaded (check the docuemntation).
I don't think that this would work in your case because you want to filter the calendar based on the resource when the user changes the resource selection during teh postback.
What you could try here is to write some custom code using the pleCode we provide with the product (check QWP installation folder) and use the form Inititilaization Action to store the value in your session then consume that from qCalendar.
Give it a try and let me know if you have more questions.