Question: Why did the ROARs congratulate Sully and invite him to join them after seemingly losing the Scare Games to Oozma Kappa?
Question: Mike and Sulley are able to activate the door when stuck at the kids camp by harnessing enough screams to activate it. If laughter is 10 times more powerful than screams, then why wouldn't child laughter (especially if there is a Birthday party, etc.) not activate doors from the "human world" allowing kids to go into the factory (monster world) all the time?
Question: Is Mike's dream where he says "But you are a princess and I am a stable-boy" a nod to "The Princess Bride", which has essentially that plot with a cameo by Billy Crystal?
Answer: Yes, the line "Mmm, I know, you're a princess and I'm just a stable boy..." is absolutely a nod to The Princess Bride. Though Billy's role, with all his genius improvised ad-libbing, is quite a bit more than a cameo.
Answer: Well a door first needs to be activated from the monster side. See the doors of the human world lack the receiver for the energy they need to open the doorway between worlds (the red light on top). That's why in the monster world they hook a door up to a machine to activate it allowing the passage between worlds before any scream or laugh is made. It costs power to activate a door to allow a monster in. Boo was able to activate doors because she was in the monster world and her screams and laughs triggered the devices on top of the doors, activating them automatically. This was the first time ever a human entered the monster world.
lionhead