The question is always the one someone is trying to answer, but I think it's funny when you ask a science-minded person... Why was the big bang something that happened? It seems unimportant and unnecessary... Thus, there is some reason why that probably gets down to something more than "it just did"... That wouldn't be a good enough answer to explain a chemical reaction in a college class let alone explain the origin of the universe. All of the creation theories are as plausible as anything science comes up with after they point; they both have ideas... and that's all they are..
We should hit these problems in a unified fashion using the lore of our past with the science of now. If we're interested in the truth we don't care where it comes from just that it is.
My pet theory was always that "God" (not Yahweh) killed itself to make the rest... Much like when you have a bacteria reproduce asexually by dividing. But, it's just a theory... It's not something I believe, but more something that I see nature do.
As far as the gaps I think the real problem is we can't get DNA/genes from fossils that are really old. We have a fundamental problem proving their ancestry due to the fact that it doesn't survive well past 250,000 years. All of the taxonomic assumptions past that time may be completely wrong -- these are educated guesses, but they are still guesses. There are four species of hominid that we know existed in that period so we have better clues, but past that... It's a crap shoot - let's separate science fact from science fiction.