Contrats: In all descriptions of the bad guys, they have beards. The father also has a beard until page 152, when he shaves it off. This is just one of the physical apperence differences you see between the good guys and the bad guys.
What is the creature the dad talks about on pages 153-154
Why do the son and father abandon the hiden shelter with the food, water and heat lamps and continue their walk in the cold weather? If I were them, I would have stayed in the shelter for as long as possible.