I don't think data really helps you get to an answer. I can only go by my experience living in America.
My observations are that Americans definitely look out for themselves. People tend to give (as you stated) in ways that directly or indirectly benefit themselves.
These are broad generalizations but having lived here for 30 years I'd not consider our society to be generous by any stretch of the imagination.
All I can say is, I am glad I don't live where you do or hang around the people you do. Having lived here all my life I cannot count the number of people who bend over backwards to help others. I watch people with half my income give money to church, charity, and the like.
Now, in the techy world I work in, I can find a wealth of self centered pretentious types who are more concerned about how their seen that what they see.
I was thinking he had pretty bad selection bias. If I applied the same to my day yesterday, you'd assume every software developer was a sharp female game hacker with a little too much caffeine in her system. ;)
My observations are that Americans definitely look out for themselves. People tend to give (as you stated) in ways that directly or indirectly benefit themselves.
These are broad generalizations but having lived here for 30 years I'd not consider our society to be generous by any stretch of the imagination.