I would agree that awareness of death is not totally absent. Seeing their associates torn apart and eaten by predators probably provides a strong connection with the end of life. On the other hand I tend to doubt that seeing others of their kind grow old and die naturally, translates to understanding the inevitable end of life for all things.

I doubt that the ability to communicate would reveal a cynical streak. If we agree that they would be somewhat simpleminded, they would probably tend toward being trusting, friendly and forgiving. Anger and rage are emotions shared by all higher species but the qualities of cynicism and non-instinctive distrust are learned traits.

They would probably be quite confused by humans.

Regarding the gifting of speech etc to primates, Robert Silverberg's Winter's End is a good fictional read on the subject.