Haven't read every post but some common misconceptions:
Part A is NOT really hospital insurance. It's inpatient insurance, so hospitals, in patient rehab, skilled nursing care. But NOT is you are in the hospital for observation or tests or other out patient services. You could be there two days having all sorts of things done and Part A won't cover it.
Part B covers out patient, doctors, DME and some medications.
Regular traditional Medicare Parts A and B do NOT cover out of the country--unless you happen to be in Canada on your way to Alaska.