truckflyer (and it seems others)
From I recall in decompression you should switch TA/RA to TA - is it not plausible that in error they instead put transponder into STBY mode?
No, that's
not in the Boeing procedure for a rapid descent.
General point and as I believe has been stated - on some 777's (if not all, customer option's and all that) the passenger oxygen is supplied from bottles located under cabin floor and aft of the wing.