There are some serious difficulties in this question, but I'm going to go ahead and I think you'll see what I mean.

The Roman world did not know such a thing as hourly wages. The urban plebs, whether unskilled day workers or skilled artisans and shopkeepers, were paid daily. We have very poor information as to the rates of pay in the Roman world. The most commonly used figure is 3 denarii per day, from a comment in Cicero that even an unskilled slave could hire himself out in the forum for 3 denarii. Nearly everybody accepts that this estimate is almost certainly optimistic, and it would have varied wildly depending on economic circumstances, but it's pretty much the only thing we've got so it'll have to do--any other estimates are largely conjectural, although frequently it's excellent conjecture. We cannot attempt an hourly "breakdown" of those wages (which we don't really know in the first place). The next-best information we have comes from Diocletian's price edict, and the wages presented there are rarely taken as fully honest--in any case the price edict was passed centuries later, in a totally different economic time!

"Caesar's time," when speaking of grain laws, is unusually unhelpful. From the time of Caesar's birth in 100 to his death in 44 as many as eight grain laws (there's some dispute as to whether some actually passed) were enacted, and the economic situation surrounding the grain trade could vary wildly from month to month. A few very basic statements can be made. By 58 all Roman citizens were entitled to receive state-subsidized grain, previously sold at the price of 6 1/3 asses per modius (a price that some people seem to think was only nominal, but in reality was more of a measure to provide grain with a stable price, not to make it affordable), for free. However, the state-subsidized grain under P. Clodius' lex de frumentaria had a limit of 5 modii per month for each citizen (probably to every head of household, and thus to the entire family to share). 5 modii was not that bad for an individual, although it'd be hard to get a whole month on that much alone, but for a family it was pretty much totally impossible. And the urban plebs had families. The mortality rate in the city was so enormously high that the urban plebs constantly had to be re-supplied, so to speak, by immigration and new births. Despite the huge numbers of people migrating to the city (especially seasonally) this alone was not sufficient to maintain the city's population. New residents were likely to die of disease, etc. and new births must have had to be constant, even alongside manumission of slaves. Women and children also appear to have worked (from what little information we have) but their employment was almost certainly irregular and it's hard to believe they brought in as much income as adult males.

The result of all this is that additional grain had to be purchased on the market, even at the high point of subsidized grain distributions in 58 (a situation which would soon change in 57, with the beginning of Pompey's cura annonae intended to combat the famine that rode in the wake of Clodius' lex de frumentaria). And here's where the real problem arises. You thought everything else was difficult? No, although it relies on a lot of conjecture. The real issue is that it's simply not possible to estimate the cost of grain at any particular moment in the Republican city. Unlike during the Principate, where grain prices were strictly regulated, there was practically no regulation in the Republic. Private grain traders traded in futures, which drove prices up, or stockpiled huge quantities of grain out of the paranoid expectation of future famines (a very real threat in the ancient world, before the Green Revolution). Cicero tells us that the day Pompey received his extraordinary command against the pirates the price of grain in the city dropped instantly to normal levels, after having been inflated many times over for some time. A month of extremely cheap grain might follow a month of extreme inflation, and there was no way to predict things. The 5 modii of the urban household provided a nice foundation, but the supplementary purchases that were required to keep an individual, to say nothing of a family, alive and fed were totally up to the whim of the market. We know from Pompeii that the staff of the local duoviri were paid between 1200 HS and 300 HS yearly, depending on their particular position. This is laughably low--in the early Principate food alone probably cost 300 or 400 HS a year. And this is in a relatively small resort town of the early Principate, in which there were some measures to maintain stable prices. In the city during the Republic we find so such measures. Rents were high--and, like wages, probably paid out daily, so that a worker unable to work for a day (probably rather common) might not be able to pay his rent and had better hope someone in the family had better luck. Food prices were irregular, and clothing had to be purchased from time to time. The general picture this presents us with is one of irregularity, but general poverty. The urban plebs were spending almost all their money on shelter and the food needed to subsist. Some months might be particularly prosperous, allowing them to live a little better, but at other times they might not even be able to purchase the grain to survive at all. Sadly even imprecise figures are notoriously elusive in this sort of work