Hi downwindabeam,
CRJs are one of the aircraft types we are allowed to turn off the Sid to increase throughput. So off 23 you get 290 to 3000 and off 05 you get 360 to 3000. If there's another V36 in front of you we can't turn you inside as Departure must provide the enroute with intrail spacing of up to 10 miles same airway. We try and turn as many of the eligible types we can. The list is expanding and includes all CRJs, ERJ135/145/175, J328 and quiet executive jets. I guess you've been lucky and not been following someone same airway!
Normally arrivals from the south and west are assigned the south arrival runway (either 24L or R depending on the operation) and the traffic from the north and east gets the north runway. Occasionally there is a need to balance the arrivals and a late switch maybe necessary. Proximity to the gate does not influence the arrival controllers choice of runway. You can ask, but don't be suprised if you get a refusal. Most of the crossing over of traffic is done on the ground, thats why it can seem like a mess at times. Traffic from the south of the airport departs from the north runway and arriving traffic lands on the north runway to park at the south and vice versa.
In Cat3 the departure must be airborne past the upwind end of the runway before the next arrival reaches the FAF. This means about 15 miles between the arrivals. In the UK the rules are different and allow much closer spacing in Cat3. Normal spacing in mixed mode at YYZ would be 4 miles at touchdown with a departure going in between.
DC