Babaleka,
To answer your question 4.
Here is a link to a list of conditions, when you do need to inform my airline but if they feel it necessary, they themselves will have already briefed the cabin crew.
Link....
British Airways - Medical information
Click on top option -
passenger medical clearance unit and then click on-
Flying after an illness or an operation
I once had a passenger tell me that he was very sore because he had had an operation in his stomach, the day before!!He was wanting some sympathy, which of course I gave him!
However I immediately informed the Captain, for obvious reasons and he was off loaded. Not only was he putting his own life at risk, he could have caused a diversion and unnecessary problems for ALL the other passengers.