Gybing - in a dinghy I would not sheet in for a gybe as long as I could head directly down wind as the boom swings across. The load is then translated directly into boat speed. In anything bigger I would sheet the boom well in before gybing.
MOB - unless I had a well trained crew and in anything but a calm sea, I would avoid gybing during MOB drill. Just go onto a reach to give enough space to tack and return to the casualty on a reach, probably just using the head sail to control boat speed.
A lot of my cruising was done with just my wife as crew and we used to practice MOB a lot. The annoying thing was that, although she had little confidence in boat handling, she was much better at MOB than I was.