Just a disclaimer before I actually ask my questions:
I am NOT an IDer
I am NOT trying to poke holes in big bang theory and am NOT trying to prove it wrong. In fact, I hold no illusions that I could even if I did want to.
I am simply curious. I do not know a heck of a lot about big bang theory, and just had a couple of questions I would like to have answered. I'm currently a second year engineering student, and I have been fortunate enough to have the opportunity to spend the summer working on my own research project thanks to a government grant, supervised by a professor in my university's physics department, whom I now work for. As I am an engineering student, my knowledge of physics is limited to what I need to know for engineering and what I need to know for my work and my research project (which focus on making semiconductors and photovolatic cells, respectively, from organic molecules, rather than the more common silicon.) I have never taken any classes in astronomy, however I do hold a great deal of interest in the subject. You should also note that as an engineering student, and not a science student, my knowledge of the scientific method is fairly limited as well.

So, on to my questions:
First of all, what is it that separates big bang theory from all of the other hypotheses? What evidence have astronomers found that only big bang theory so far can explain? The extent of what I know is that astronomers have discovered that all galaxies (or clusters of galaxies, at least) are receding from each-other, and from that they have deduced that the universe is currently expanding. But my question is, why is it that the universe neccessarily had to begin as a singularity? Why could it not have been contracting at some point, eventually halting before becoming a singularity, and beginning to expand again?

Second, how are scientists able to look back and determine exactly what was going on as little as 10^-44(I think) seconds after the big bang happened? How are they able to deduce this, and how are they able to be certain that those deductions are accurate?

Third, and this one is a bit tricky - I understand what is meant when it is said that the universe is expanding, but only to a certain extent. Does it merely mean that the distance between any two clusters of galaxies which are stationary with respect to each-other will always be increasing and that there isn't actually a finite amount of space (ie. I could fly off in one direction, and after leaving the "universe" behind, I could just continue flying on into infinity, while the universe behind me continued to expand, and the space separating me from it along with it) or does it mean there is actually a finite amount of space which is ever-increasing, and the universe is actually enclosed. If it is the latter, what happens on reaching the "edge?" Would the universe simply loop in on itself, and you could just keep going in the same direction, and eventually return to the spot you left without changing direction (like the world map in final fantasy games) or is it warped in some other way so that you can never reach the edge, or is it something else altogether?

Finally, I had one last question: If the singularity from which the big bang initiated was purely energy, and all of the matter that existed today came from that energy, then how was the imbalance of matter and antimatter created? Shouldn't there have been exactly equal amounts of each? Where did all of the extra matter come from, or what happened to the antimatter that should have arisen along with the matter that does exist?

Thanks in advance for answering my questions.