Ilduce, why do we want Serfdom??? I have to admit that I have almost never used Serfdom. OK, so Workers Work faster, but that's not nearly as strong as Slavery's ability to turn food into hammers, or even Caste System's allowance for infinite specialists and a boost to workshop's production. Rather than adopt Serfdom, I just build more Workers. It has Low Upkeep, yes, which I assume is the draw for you, but civics with higher upkeep have higher upkeep for a reason (they are generally stronger).
I do agree with Arya that we should not use a flat number for defenders in our city. Ideally, we want to defend our cities, especially the backline ones, with as few troops as possible to save on upkeep costs. Kind of the irony of Hereditary Rule, I suppose, but it's still better than Despotism.
I still disagree about the extent to which we should war, though even if we were planning to grab most of Rome, I'd still advocate focusing on the lusher fields of central Europe rather than the Italian Peninsula. We're behind technologically, so we really don't want the war to drag on longer than it has to. I suppose it depends on how much assistance LH is giving to Rome (still not entirely sure why--story reasons??), and how much progress Rome makes against Russia, but so long as we end the war on our terms, we can be prepared for another one.