Good question! That can depend on the conditions in your dark room and the emulsion used and even the coating technique used. If you working in uncontrolled conditions, I would recommend using the unexposed screen within 48-72 hours.
Not necessarily! It truly depends on the humidity in your space. Control that and bring in fans and when you can, pick yourself up an enclosed drying cabinet!
The dark room temp should be between 70-80 degrees but the screen drying cabinet you're referring to can be at a higher temp to dry your screens faster.