I'd like to note that you never know when AMS will strike or how hard. I have hiked all over and usually the most I get is a lack of appetite.
The only time I really got questionable symptoms was at lower elevation: hiking SoCal's San Jacinto from the tram. Once, of the three times I have done it, somewhere near switchbacks at 9k I had to sit and rest
Yep, 9000 will do it, in fact, current official threshold is 8000 and some talk of 7000 .
Yep again, a lot of unpredictability about who , when, where, other factors
Need more than loss of appetite at high altitude to make a diagnosis of AMS. See Lake Louise Score of AMS
