Yes, they laughed, supported each other, had doubts about whether they would survive, and cried over the loss of fellow servicemen. But I dont think the men of greatest generation ever 'whined' or complained like the soyboys of today (as portrayed by Hollywood and by liberals) are expected too. Drama queens would get no slack or respect in real life.
Perhaps not, but they did talk to their friends in the service about their fears (again, this fact is in their writings) and some of that is going to be in the film.