Thank you for the welcome and the insights. I appreciate your response!
I was unaware of much of what you said about the Grachi and about the restrictions of the priesthood.
Through the election of consuls, weren't generals often basically elected anyway? My understanding is that Marius was re-elected so many times primarily because of the repeatedly delayed threat of the Cimbri and Teutones. The people kept electing him because they felt he was the man who could protect Rome. They weren't electing him for any other reason, at least until after they were defeated, were they? I do understand that the Senate engaged in some political trickery (and I use that term loosely) after his initial election and that another vote was required to send Marius after Jugurtha, but did this really seem outlandish to Romans at the time? It evidently did not to the voters.
Well Caesar's decision to give clemency to certain Romans seems to have been a miscalculation in any case. I'm not sure I would call it colossal, though. I think Caesar would be fairly satisfied to know that he is still frequently talked about 2,000+ years later and is generally considered one of the greatest (in terms of importance) men of all time, in any culture. Couple that with the fact that we all have to die sometime, and he could have done worse for himself.
As for the fall of the republic, I suppose it can be fairly said that it was indeed caused by Caesar, but personally I'm more interested in the factors that allowed him to do what he did. It seems like the stage was set in the time of Sulla and Marius, and that this era of conflict was in turn set up by the actions of the Grachi (justified or not), and my feeling is the republic probably would have fallen even if Caesar had never existed. Of course there is no way of proving that.
For whatever reason, it seems a large majority of people became very distrustful of the Senate. Marian reforms had made soldiers beholden to their commanders, allowing those who commanded them to command their almost total loyalty as well. So in hindsight it is no wonder that politically savvy generals would be able to work the people, so to speak, to circumvent the laws and traditions of the republic for their own advantage.
I think the million dollar question is what things were the cause of this mistrust between people and Senate, and to what extent those things were real or just perceived. Also, to what extent was the Senate more of an oligarchy than a part of a republican power structure? To what extent were the people cruelly manipulated by people like Marius, Pompey and Caesar, vs. the people getting what they wanted/needed out of those men? I find it difficult to answer those questions, but they seem central to the matter.
Edit: I see I will have to work on my quoting skills! I tried to make it somewhat more readable by italicizing things Cato said and eliminating my original quotes altogether. Sorry, I did preview it and thought maybe the quoted parts just didn't look right until the end product.
[Edit PP: you were missing a couple of quote tags... added them in]