One More Movie Trivia as We Move Toward Long Underwear Season!

Take a close look at these scenes from a popular film a few years back, Union Suit Fans, and give us your best answers to the questions below:

From what movie are these scenes taken from?  

One character wears only long underwear for pajamas. Who is the boy in his union suit pj's?  

Why is his face partially covered in bees in the first photo?

Why did the kids don gas masks?

Name three peculiarities of any three of the kids? 

One of the three main characters in this film is a 16 year old boy? Who is this young actor, and what is the name of the character he plays?