1) Our current understanding of evolution has been much more influenced by the newer science of genetics than of Darwin. In the 1830s, the only inkling of heredity came from simple mendelian genetics that I'm sure most of us have done in high school biology. He set out looking for evidence, for fact not myth. There is a lot of mythology in creation stories from around the world with small kernals of truth buried deep within. He did not set out to disprove the establish religiously based view of creation - in fact he held off on publishing "On the Origin of Species" for a solid twenty years after his expedition on the Beagle while he tried to reconcile his orthodox views with the evidence he had amassed, which ultimately led to his transition from orthodoxy to agnosticism.
Descendence from apes is a tricky concept for many people because of our ingrained belief that human are elevated about all other life forms. The idea that we are not as different from the animals as we would like to think can be quite unsettling. When you look at the physical evidence (anatomy) it makes sense. As I am no where near as eloquent, here is the last paragraph from "Origin of Species" (of which you can find the entire text online):
Man may be excused for feeling some pride at having risen, though not through his own exertions, to the very summit of the organic scale; and the fact of his having thus risen, instead of having been aboriginally placed there, may give him hopes for a still higher destiny in the distant future. But we are not here concerned with hopes or fears, only with the truth as far as our reason allows us to discover it. I have given the evidence to the best of my ability; and we must acknowledge, as it seems to me, that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system—with all these exalted powers—Man still bears in his bodily frame the indelible stamp of his lowly origin.
2) Survival of the fittest is not what we have been led to believe it is. It does not mean that the biggest, strongest, most aggressive survives, but that the one who can adapt the best will outlast all the rest. Our notions about social darwinism, a dog-eat-dog world, all came later and would have been considered deplorable by Darwin. Evolutionary fitness is defined by who has the most offspring survive. This is in direct conflict with social hierarchy stating that those at the top of the pyramid are the "fittest" and therefore deserving of our power and esteem. The octomom is evolutionarily more fit than Bill Gates. Shocking, and yet it makes sense. While not all of her children will survive and thrive to produce multiple children of their own by sheer statistics, her traits - both genetic and cultural - will have a much greater chance of conquering the world than Gates' three kids.
The public's understanding of the time-scale for evolution is all wrong. For those who don't know, evolution happens on a species level over many generations. Adaptation happens at the individual level. You cannot watch evolution happen, unless you are watching fruit flies or some other species with a super short rate of generational turnover. At the time of Darwin, he posited that natural selection was just one of a variety of mechanisms leading the evolution. With the rise of genetics, it has been shown as the only viable means of evolution.
Change over time to adapt to pressure. That's it, the whole controversial concept. It's a very simple idea, one that to this day still gets people's feathers ruffled. Look no further than the continuing debates in schools about the teaching of evolution versus creationism. Science and religion are not antithetical by nature, they only become that way when people in power on either side feel threatened. In other words, they feel the need to fight for their ideology's survival, which is ideological survival of the fittest. It all comes full circle.
Darwin was a great naturalist of his time, who had made many important observations. For instance, it is because of Darwin that we understand how coral atolls form or how barnacles work. He wrote many books and some of his more interesting and innovative work is found in "The Descent of Man", which talks about sexual selection, and "The Expresssion of the Emotions", which is one of the founding works of psychology and hugely influential on Freud. His work has revolutionized science, indeed it helped lead to the development of scientists - as distinct from the more clerically trained naturalists. He was seen as both heretic and herald. You cannot have a complete understanding of how Homo sapiens are now without understanding the thought process that led us to start looking for clues about the world around us.
