Re: AoA sensor replaced prior to fatal flight
It appears, based on reading the FDR data by people more knowledgeable than me that the previous flight's pilots had overcome the MCAS issue by diagnosing a failure that required isolation of the trim system. As they didn't know about MCAS they wouldn't have known that's what the problem system was but the effect was to remove it from the equation anyway. However this may have meant the next crew were starting from square one when it came to diagnosing what was going on with the various issues that they were presented with or have been primed to expect a reversal of the usual trim system rather than starting from scratch. Neither of which are great situations to be in.
'Has the cockpit been found to determine the state of the MCAS switches?'
There aren't any as such, and the pilots weren't told it existed previous to the accident. The trim cutout switch position can be determined from the FDR and I believe they hadn't been activated at the time of the accident.