While the cabinet is defrosting the display shows a fixed temperature; is this normal?
Yes, because the display shows the temperature there was inside the cabinet when defrosting started.
As soon as defrosting is finished the display again shows the actual temperature inside the cabinet.
Can the doors be opened on the right and on the left?
Yes, as for the chilled counters, the doors can be reversed even while they are being used but no kit is required - reversal is easy.