Not sure but there may be a Q400 that miss' out the early wave rotations to act as a spare or back up until the CGN. I will need to go through the schedule properly when I get some time but the connections timetable seems very accurate (more so than the standard!)
With regards to Monarch, I had been given the impression that Menzies were expecting to get much busier. I cannot imagine this was just based on the increase in BE flying so maybe the rumours you heard OP were correct.