regarding the transponder.
if you had made 12 attempts to contact atc via vhf radio and didn't get hold of anyone, wouldn't you at least think about selecting 7600 in the transponder...mind you I am not saying to do it just yet, but at least think of it?
honestly, if I hadn't had any radio transmissions in a certain amount of time, I would look at my tcas to see if there were any other planes nearby for a relay or at least a radio check.
and when looking at my tcas display ( unless it is one of the real small cheap ones) I would certainly see any warning that it wasn't working because my transponder was off...
just questions and not judgements yet.
pilots do have to think and question and consider situations.