I would really think she is having some less extreme procedure done based on her attitude and that of the whole family, but I'm sure she spoke of seeing a plastic surgeon for "reconstruction" so it must be something serious, unless it's all manipulated to let us think it's PE surgery.
As far as how the family all seems so celebratory and unconcerned about her life altering surgery, I remember in the clown car discussion after they had spoke to the surgeon about tumor growth etc, for three hours, they went out for a big Italian meal! I know Matt said he was too hungry to go straight home. I mean who does that, I've had family members receive bad news regarding cancer and the last thing you do is go out to eat??!!!!