Barricades?

[Barricades?]

I have read the rules and through the forums about barricades. I am still trying to get a handle on them.

• If I barricade myself into a room with only the one door, am I able to unbarricade the door to get out of the room? 
• If there is a barricade in a room with multiple doors, can I move it to any door or just doors in the space it was placed? 
• Does breaking through a barricade cost a monster an action? If it breaks through, does it still attack an investigator? 

Thanks!