Not really, no. The Victorians liked to think of the political struggles of the 1st Century, B.C. as being between "populares" and "optimates," which is simply untrue. What's more untrue is that those groups were anything resembling modern political parties in any way. The idea of an organized political faction would be totally alien to a Roman, for whom politics was a pursuit of individual ambition and intense personal competition. The categories of "populares" and "optimates" are not ones which appear at all in antiquity, but are modern labels applied by Victorian scholars to try to make sense of the political trends that were sweeping through Rome at the time. The terms themselves are rather problematic, but certainly thinking of them like political parties is erroneous. They had no organization whatsoever and no planned program or platform--indeed, people that are often labeled as being in the same "camp" quite often fought viciously with each other. It's also not right to call them a political faction, since that implies an idea of a group of people working consciously towards a common goal. More realistically these guys had similar individual goals in mind, and were willing overall to align themselves with each other, although not at all generally. It's made more problematic by the fact that the populares and optimates only can really be said to exist for a very short time--well, the populares anyway. The optimates persisted for some time (after all, their name simply is an indication of the oldest families of senatorial rank) but the populares died out rather quickly after Marius' death, partly because Sulla killed most of the Marians but also because with the dismantling of many of the elements of Sulla's constitution their goals had largely been accomplished. It's certainly erroneous to call Caesar or Clodius populares, at least if we mean a member of that particular faction (and here I am using the word faction, as we don't really have one in English to properly describe the relationship--see how troubling such exact terminology can be?) rather than guys who generally proposed populist legislation. The optimates in particular should not be thought of as a political unit in any way. While the populares under the Marians had a rather general set of goals that they tended to stick to, the optimates did not at all--they're simply the body of old senatorial families and those that support them, with no other goal than to preserve their own rights.

Yes and no. The political fighting of the roman politics that lead to the civil wars are often summarize in the opposition between the populares (favorable of the plebs) and the optimates (favouring the aristocratic favours). But it's clearly not that simple. Julius Caesar was an aristocrat looking for votes through popular reforms while Cicero was an homo novuus (a new man who had no family in politics) favoured the aristocrats. This simplification would tend to see the populares as those who care of the people. Even if thatis partly true, as Caesar expanded greatly the distribution of food to the poors of Rome, it was also a way to make all those new people dependent of this help, increasing is number of clients and as a consequence, expanding the potential of voters/recruits. Finally those factions had no legal/constitutionnal values but was born by the alliance of important to a common goal, adding their clients to help the elections of their friends. So they emerged from the polarisation of Roman politics.