Sorry to hear about your dad's problem. The first thing you need to find out is the stage of the cancer, as the management is dependent on that. The staging can only be done after a few imaging tests (CT, X-ray chest, etc). You should also inquire from the surgeon about the management plan once the staging is over.
Your dad must be on aspirin
and that has to be stopped atleast 7 days before surgery, that is the reason your family doc must have asked to stop the medicines.
Hope you father gets well soon.