The YUL-PRG flights are not on ANY of the on-line schedules I have looked at. However, apparently, DL can use any of four US gateways for OK (EWR, JFK, YUL, YYZ).

As far as PRG is concerned, I have no clue where I will be staying. I am arriving and heading directly to meetings on Friday and all day Saturday (through a late night dinner). I plan to take part of Sunday off and wander around. But, I've never been there and any suggestions would be welcome.