To answer the "Should you open it from time to time" question.
Depends on the window
There are 3 kinds of "latches" that I know of I've actually seen/used two of them
On my coach each emergency window has a pair of red handles. You turn them, then push the window open (it swings up) I have used them, for example, to pass boxes (Flattened corrorgated paper boxes) directly into the bedroom for transport. (We layed them atop the bed) also for entry/egress when the door latch broke.
On most Detroit City Buses it's a full length bar along the bottom of the window..Pull up and push out to open.. I've only closed these. Never opened one. But again. you can open and re-close these.
Some rigs have a "rip cord" type of thing.. You pull a rip cord and it tears the rubber gasket you can then push the window out... These can not be re-closed.
Every person inside the coach should at least know HOW to open the emergency exits.