unfortunately, your problems can't be solved with Set Analysis alone... Set analysis conditions are checked once for each chart (not once per each cell), and therefore you can't compare Key Date with AdmitDate and Discharge Date within the Set Analysis.
The "right solution" should be found in the data model. Depending on the type of the link that connects your Key Date with Admit Date and Discharge Date, you should be able to add a flag to those transactions that satisfy the date condition. If you have such a flag set to 1 for all the "relevant" records, then you can use Set Analysis in the simplest way:
The specific logic of adding the flag depends on your specific data structure.