"Class struggle" is a phrase that, for Roman history, means a lot less than I think you realize--as the New Pauly puts it, "Attempts to collate ancient SC [Social Conflict] under generalizing headings such as 'Struggle of the Orders' or - primarily in Marxist scholarship - 'class struggles' remain controversial." You're also asking about an enormous period of time and seem to be mixing up stuff from different periods of disorder: the successful campaign by the plebeian order to secure equal political rights in the Conflict of the Orders (which was over very early) has little to do with the violence among the urban plebs in the 50s and even less to do with the social struggles of the Principate. The Conflict of the Orders and all that has next to nothing to do with the social conflict of the late empire. There's also quite a lot of controversy about social struggle within the Roman, and particularly Republican state: the precise nature of Gaius and Tiberius Gracchus' relation to the urban and rural plebs, and what exactly the Social War was come to mind immediately, and within my own research there's a lot of reason to suspect that the usual narrative of the Clodian violence of the 50s simply can't be right (it doesn't make sense and is based far too much on assumptions made by Mommsen that were either not backed up or have been shown to be false). Just within what you've asked the role and nature of latifundia are hotly contested--there's a major disconnect between what archaeology shows up and what our texts tell us as far as large estates on and off the ager publicus go.

Good, readable overviews of the complexity of Roman social interactions are, in my experience, rather hard to find. Social interaction is more than just overt struggle or violence, and social interaction is, naturally, apparent in every aspect of the study of the Roman world. I know of no particularly good overview of all social conflict throughout the entire history of the Roman state, which would be kind of a bonkers project--the Cambridge histories may be nice to give some grounding, but besides that I can't think of anything off the top of my head. The most complete treatment of Republican social conflict is Brunt's book Social Conflicts in the Roman Republic, but it's from 1971 and is extremely dated in places (Brunt's treatment of latifundia is, as I recall, totally obsolete). Brunt also had some particular views that, like any historian of Roman social conflict's ideas, are very contested and were even at the time. People are always arguing even about matters of Roman social interaction that should seem straightforward.