Unfortunately, I have had to edit your question down to one question, according to enotes regulations. Please remember to only ask one question.
I think you are absolutely right. Cormac McCarthy is obviously playing with the archetype of the journey in this terrifying novel, and we are presented with the father and the son who are setting out on a quest to reach the sea and escape the winter which they know they are unable to survive. Like Homer's work, they meet various characters and go through various challenges to their survival on the way, and although they are successful in their quest, it is only at the cost of the life of the father, who leaves his son in a perilous, uncertain position in a desperately uncertain world. Although we are given a "happy ending," the setting in a sense undercuts that happiness, as there are still many challenges to be overcome.
With such an archetype, though, what you need to focus on is how the experiences of the journey shape and form the two central characters, in particular the son. Note how he is obsessed with "the good guys" and "the bad guys." It is he that remonstrates with his father when he acts for their survival in this dog-eat-dog world, and he seems to problematise the distinction between good people and bad people, suggesting that on the whole everyone is just engaged in a desperate struggle for survival.