1 hour and 19 mins should be just fine. In January I flew through YUL with a 1 hour layover, which ended up being a little less because our plane was late landing (only about 5 minutes). It was a Wednesday morning around 7am, and from the time I got off the arriving plane until I was seated on the plane to MCO was about 30-35 mins. There was really no line at all at that time, just a couple of people ahead of me but it seemed like they had a lot of agents there so it moved very fast. From what I understand there is a separate area for people who are trying to make connections to go through.
Your bags do go straight through, you won't see them again until Orlando. When you get off your arriving flight you just need to follow the purple "Connections" signs with the US flag on them, it is very straightforward but can be a pretty long walk depending on which gate you arrive at.
My fingers are crossed for you, hope you have a smooth flight and a great trip!
