Bathroom remodel - Questions about Code on 2 vapor issues

Hi I have a house built in 1920 and a bathroom with a clawfoot tub. I have taken out the walls and put in insulation and will put backerboard on the bottom of the walls (for the tile) and green drywall for the top. To be compliant with code my town tells me to look at the 2006 international building code for answers to any questions. I look but am not finding answers.... so:

Question 1: If I have a window that opens to the outside in the bathroom, to be compliant with building code, do I have to put in a fan to exhaust to the outside or is the window sufficient?

Question 2: For insulation in the walls, I have Kraft paper insulation with the paper faced into the house. Is this sufficient? Should there be no paper, just bare insulation? Or should there be a vapor barrier, like plastic between the insulation and the backerboard/green drywall?


THank you!