She already revealed that Robert Pattinson‘s the coolest celebrity dad, but Mackenzie Foy‘s still got plenty of Breaking Dawn — Part 2 on- (and off-) set secrets to spill. During Teen.comchat with the soon-to-be 12-year-old, she opens up about her first meetings with Rob, Kristen Stewart and Taylor Lautner, her most embarrassing moments, the cast swear jar (yup, that happened) and her love for…