Very good questions you've raised, anakolouthos.
I think that the first thing you need to keep in mind is that biology is a relatively young science, historically speaking. It's only a little more than half a century since the existence of DNA was discovered. Only in the last 15-20 years have geneticists begun mapping complete genetic codes. This very recent science is making discoveries about biology at an amazing pace. So one can hardly expect science to have all the answers.
This has historical precedent. Physics made great advancements in the 17th century with the discoveries and theories of Isaac Newton and others. But it was another 250 years before Einstein and other scientists made huge advances in understanding, with relativity and quantum mechanics. When these later scientists changed physics, they didn't invalidate Newton's and many others' theories, but expanded upon them and showed that the earlier ones were subsets of the newer theories, and had been limited by observation techniques and theoretical understandings.
You need to keep in mind that evolution has several aspects. One is the historical aspect, based on paleontology and geology, which shows that life has evolved greatly over time. Another is also the theoretical aspect, which is concerned with why and how life has evolved. The former is what scientists often call "the fact of evolution" while the latter is generally subsumed under the term "theory of evolution".
The fact of evolution is so solidly confirmed that, as Stephen Jay Gould once said, one would have to be perverse not to accept it. It's as solidly established as anything in science can be. We know that the earth is about 4.6 billion years old, that life was on it by 3.5 billion years ago, that the first macroscopic life appeared some 600 million years ago, that the blossoming of life sometimes called the Cambrian explosion occurred between about 540 and 510 million years ago, that 90% of life on earth was killed in the great Permian extinction of some 240 million years ago, and that the age of dinosaurs ended and the age of mammals began about 65 million years ago.
The best large-scale scientific theory of why and how evolution occurred is an extensive set of modifications of Darwin's theory of natural selection. A great deal has yet to be done on these ideas, and certainly even more on the genetics of what happens. The science of ultimate origins is barely in its infancy, both in biology and cosmology.
Now, I suppose that some sort of creative force might have directed the evolution of life during earth's long history, but given the actual history of life, this raises a number of huge questions that are not amenable to solution without direct revelation from this creative force. And the Bible demonstrably doesn't cut it. I hope you see my point.
An interesting conundrum for strict creationists is the origin of God, as pointed out by Carl Sagan more than 20 years ago. They claim that "life comes only from life" -- except for God, who has "always been" and is "outside time". But if God has always been, then why not the overall universe? I'm not talking about just our local universe, but the entire macroscopic universe of which our local, observable one might be just a miniscule part. In such a macroscopic universe, infinite in extent and time, all things are possible. Speculation? Sure. But so is God.
No one knows the origin of sexual reproduction. The best one can say at present is that, once it got going, it had the potential to produce far more variations far more rapidly than asexual reproduction. Even strict biblical creationists acknowledge this, since they can observe the evolution of viruses and bacteria, and they even claim that massively quick evolution must have occurred immediately after Noah's Flood. No one knows the limits over the long haul of this evolution, so distinguishing between micro and macro evolution is mere semantics.
The website you gave a link to argues essentially what all other creationists do, that is, invoke "the argument from ignorance": "We don't understand how this thing happens, so it must have been by a miracle." Imagine the confusion of a 1st century skeptic examing the workings of a modern computer system -- he would conclude that a god was doing it.
The only way to learn more about evolution is by actually getting down and doing it. There are plenty of resources. The best online resource, IMO, is www.talkorigins.org. You can find excellent popular treatments such as Richard Dawkins' books. You can get hold of introductory college texts, or even take a course or two. My daughter recently completed Evolution 101 and was amazed at what science really says and the real world holds, as opposed to what the JW training she received as child taught her.
AlanF