Hi Sureshaus, As far as your problems with natural selection, all of the questions you have asked, have in fact had pretty comprehensive answers. Might be worth your while, reading a book on evolutionary biology. Dawkins's latest requires concentration, and he does tend to be a tad rude about lazy and illogical thinking, but I think the explanations for your questions are there.
Probably worth reading before you start the film. Be horrible to have a "Road to Damascus" moment half way thru. cheers