After all that drama and angst, it turns out the lawnmower was not as bad as I originally thought. In fact, there was nothing even wrong with it. As I mentioned before, I did everything I was supposed to do as a real man in training: I changed the oil, replaced the air filter and spark plug, put in a new blade (this was extra), and I even cleaned the carb. After all that, the thing wouldn't start despite repeated tries on my part. I took it into Joe's and the person helping me tried and couldn't get it to go, either, so I had to leave it there for repair.
A week and a half later I called them and they said there was nothing wrong, after all. The mechanic primed it and gave it pull and the thing started. Can you believe that? It's a bummer because I had to sit and watch the grass grow during that time, which was a warm spell, and I had to drop $30 for their time even though no repairs were done. I think he tightened the pull cord, which I guess is not nothing. On a bright note, however, it also means that I'm doing everything right and at the very least had not destroyed it. Sometimes you just have to look at the bright side of things.
Until the next time, thanks for reading, and thanks to Kristin for the pic.