According to
The Guardian livestream, a 4U rep confirmed that the last C-check had been in the summer of 2013, and the last A-check the day before the flight.
Also,
B) the autopilot descend quickly in the way we have seen?
There was
this incident last November, where an LH A321 went into an uncommanded dive due to malfunctioning angle of attack sensors. The crew managed to recover after disconnecting ADUs. Not wanting to speculate as to the reason for the 4U crash, but there do appear to be similarities.
A lack of radio communication doesn't necessarily mean the crew was incapacitated. Perhaps they were so busy trying to recover the plane that they simply forgot to make a radio call. Unlikely of course, but everything that happens in regards to plane crashes is unlikely
Not that unlikely. IIRC, the mantra goes aviate, navigate, communicate - in that order. First you make sure you're not falling out of the sky, then you make sure you're not going to crash into anything else anytime soon, then you can start calling for help.