Sure, some previous generation specimens could be better survivors than their progeny - but for the most part, the cycle of the creation of many offspring with mutations and the dying off of the previous generations provides most of the evolutionary "force".
No, because characteristically, organisms dominate niches. Previous generation's ability to move out of the way prevents new generations from getting a chance to try out their new mutations.
That's not true. An previous generation might actually be better suited to a particular environment than the current generation.