Remember how I started my post on Greece by saying there is a lot of variation? Well, the Roman Empire was bigger, more populous, was more economically complex an more diverse than "Greece". If this weren't enough, it also lasted a longer period of time, so I will confine myself as much as I can to the early imperial Period or "High Empire", and I will try to specify region as much as I can.

Also, if you want some nice articles or chapters to assign for reading, The Cambridge Companion to the Roman Economy will be a nice place to start. If you are trying to do historiography you are in luck, because this discussion has been raging for centuries, and economic history and thought at least as far back as Defoe has often used Rome as a starting point. One of the reasons for this is that Europeans until very recent centuries were confronted by the fact that there were an awful lot of really rather enormous stone ruins scattered about and were forced to ask themselves how, exactly, those got there. Answers have included slave economies, imperial aggrandizing, colonial economics, integrated market economies, cultures of public display and more. If you want to throw two arguments against each other, you can compare the great early twentieth historian Mikhael Rostovtzeff, who saw an economic system very similar to that of his own, and Moses Finley, who saw something strikingly different. More recently, two of the more prolific dipoles are Peter Bang, who sees an essentially imperial economy governed by status relations, and Peter Temin, who sees an integrated market driven by laissez faire economics. The more things change etc. I'm happy to give specific recommendations if you would like.

What were the common productive units? Family farms engaged in subsistence production, commercial agriculture by tenant farmers, slave-labor-dependent plantations for cash crops?

The bare majority of people across the empire would have been engaged in farmer which was primarily for their subsistence (although what proportion is of course impossible to say). I dislike the term "subsistence farmer", however, because I think it is overly essentializing: a very poor farmer in the Siberian taiga is in a fundamentally different situation than one along the Nile. They may have been disadvantaged, but they were still part of the greater economy, both in that their produce would be used to create elite surplus and that they bought and sold goods within the market. In fact, the rural economy even seems to have been monetized--there is a study on this using Apuleius' Golden Ass that I will post when I find. I also would rather not describe them as "marginal" except in certain situations, such as northern Spain or Issauria in southern Anatolia.

Beyond that, tenant farming, communal farming, slave plantations and independent yeomen all existed. Elite level agricultural economics is, as always, the easiest to study, and for that I tend to follow a model of predominantly tenant farming because I feel the slave plantation model relies too heavily on an inapt comparison to the unusual circumstances of the New World. They did exist, of course, but they existed in tandem with other forms, and even the slave plantations described by Columella used seasonal hires during plating and harvest.

The question of cash crops is always difficult, both because it seems to assume a position of market economies and also because of determining specific agricultural activity is always difficult. Should we follow a cash crop model, or one in which villas aim for “self sufficiency in all, surplus in some” (as one archaeologist described)? The literature tends to emphasize self sufficiency and diversity of produce (although this is complicated) but can we take these as actual indicators of practice? The archaeology is no less complex. In certain regions, such as southern Spain, survey archaeology has produced a more or less irrefutable argument for mass commercial production of olives, but is this model applicable to other regions?

All this being said, what survey archaeology there is (which is disproportionately in the Latin West) tends to favor a rural organizational model of dispersed settlement characterized by homesteads and small hamlets. The Pax Romana seems to have allowed for a more dispersed pattern than was possible before or after.

How was labor organized in different places and different sectors? In my research on 19th-century British bakers, they never cease to refer to the history of bakers in Rome, which they view as a kind of golden age in which baking was a well-regulated, respected trade, organized into a sort of urban guild system. Did Roman cities have guilds to regulate various trades? How important was slave labor? What differences do we see between urban and rural settings, or between different parts of the empire?

Sort of, maybe. The most well known labor organization of sorts in the Roman world was the collegium, which became prominent and important seemingly everywhere across the empire, although the specific modes of organization seem to have differed. For example, merchants in the East seem to have primarily organized themselves along communal lines (religious, ethnic, familial etc) while evidence from Lyon seems to point towards merchants organizing themselves along specific goods carried. This, of course, is not easily applicable to other professions, but it shows some of the diversity.

Anyway, collegia seem to have begun as religious and burial organizations, but they quickly acquired commercial and social characters. This is all rather difficult to untangle and requires using a lot of varied evidence. I'll just give three, to give an idea: In Egypt, the environmental conditions allow for the survival of documentary papyrus and so we know an awful lot about collegia there, and we see a great deal of market organization and negotiation in the documents. In Asia Minor, literary evidence allows us to see examples of certain workmen organizations opposing the activity of the imperial elite (specifically the orator Dio Chrysostom) and prevailing, their collective economic interests defeating a very well connected person's political interests. In Pompeii, we see graffiti showing the prominent social role of collegia, and we even have wall paintings of something like festival floats. The problem with integrating is that these are fundamentally different types of evidence—we have no grafitti and wall paintings in Egypt, no papyri in Asia Minor, no literary descriptions for Pompeii. So are the role of collegia the same everywhere, but we just have different sets of evidence? Or are they actually very different?

I have to go right now, but I'll post the rest when I can.

Here is a quick overview of crops grown in Roman times, which might help with some of your question.

In Roman times, the main crops in Italy were: Wheat (“spelt” wheat which has been replaced by “common wheat” these days), millet, wine grapes and olives.

Other crops grown were, artichoke, mustard, coriander, rocket, chives, leeks, celery, basil, parsnip, mint, rue, thyme 'from overseas', beets, poppy, dill, asparagus, radish, cucumber, gourd, fennel, capers, onions, saffron, parsley, marjoram, cabbage, lettuce, cumin, garlic, figs, grapes, 'Armenian' apricots, plums, mulberries, and peaches.

Many of the main crops grown in Italy today, such as, (in order of production in modern Italy); sugar beets, corn, tomatoes, oranges, potatoes, apples, and rice, were not grown in Roman times. They had not yet arrived in Europe from either the New World, or Asia.

The Romans raised cattle, mules, horses, donkeys, sheep, goats, pigs, and fowl. Also fish (which they farmed as well as caught). They did not raise the Water Buffalo, used to make buffalo mozzarella cheese in Italy today, as these did not reach Italy until Medieval times.

Sources: http://www.nationsencyclopedia.com/Europe/Italy-AGRICULTURE.html http://en.wikipedia.org/wiki/Buffalo_mozzarella#History_in_Italy http://en.wikipedia.org/wiki/Roman_agriculture

May I have a link to your Greek one? Having trouble finding it on mobile for some reason.

Another related question : Has anybody read The New Deal In Old Rome ? I read it 2-3 years ago and I was really interested by the topic covered. It was written in the 1940s so I do not know if there has been anything new in history regarding the Roman economy. I am not a trained historian so I do not think of myself as a good judge on the academic quality of this book, but it might interest you OP.