Re: The Roman Empire?
 

slave labour was both an economic and a social factor in the decline of rome. i'm not saying that the roman empire fell exclusively because ot slavery, but it was an important contributing factor. wealthy romans had slaves work on their farms and as servants in their homes the number of slaves grew dramatically in the later centuries of the empire. a wealthy roman could easily own thousands of slaves. the land owners became dependent on vast amounts of slaves. this heavy use of slave labour forced working class romans out of their jobs. (why pay wages to workers when you can buy slaves who do it for free?). thus working class citizens could not compete on the job market and went without job. this created a large (and growing) group of unemployed lower class citizens who needed to be pacified. this included free food and entertainment. municipal buildings such as baths and theatres had to be maintained and food had to be bought for the 'plebs'. these free services didn't generate a revenue so it was money directly out of the treassury. then, of course, there was the internal security issue. once slaves are employed, they don't just 'forget' about freedom. an estate with, say, 2,000 slaves creates an obvious security issue. you have to have troops stationed around the empire (not just at the frontier) to supress any possible slave uprising (ever seen the film spartacus?)
furthermore, if the mob was unhappy or angry, it could lead to civil unrest which then had to be quelled by troops who could be at better use protecting the borders. during the final years of the empire there were more slaves in the empire than citizens. suffice it to say that that is an unstable situation in the long run.

Re: The Roman Empire?
 

I have, but - more importantly - I have read the sources that mention his rebellion, and several books that discuss it :).

Furthermore, your analyses is correct for the late republic. Funny part is that the rebellion of Spartacus took place in exactly that time :).

This is incorrect for the empire: with the end of most of the offensive wars, slave supply fell low. During the republic Italy, Spain, Africa, Greece, Gaul... were conquered. Conquests under Augustus remained limited (some small wars against tribes in the Alps, Spain and Illyria), limited to Egypt and some small extras. Claudius conquered Britian, Trajan Dacia. There were attempts to conquer other countries, but they failed/were given up (see Hadrian and Mesopotamia). This ended the constant influx of warslaves. Furthermore, the conquest of so many countries meant that influx into the empire from uncivilized areas became more limited. Britain and Gaul had supplied many slaves by trade - traded for, for example, wine. There were areas that supplied them, yes, but peaceful slavetrade didn't bring in 200000 slaves at once. [Figure from Stöver (H.D.) Romeinen. De geschiedenis van een machtig wereldrijk.]

In short, slave supply in the late empire fell low. More slaves by breeding took time. Part of this explains the laws, introduced by several emperors, for a more human treatment of slaves AND the limitation on freeing of slaves (under Augustus it had become a 'fashion' for the rich to free slaves, cf. Suetonius De Vita Caesarum). Apart from that, Caesar and several emperors realised the disadvantages of slave labour, forcing rich landowners to employ free people, apart from slaves (for Caesar: Suetonius).

Part of this has been refuted. Furthermore, there was a mass of unemployed citizens, but this phenomenon was - mostly - limited to the city of Rome. Modern scholars also believe that the mass wasn't the jobless scum they are made out to be by aristocratic writers. [See, for example, Mouritsen (H.) Plebs and Politics in the Late Roman Republic. I think Lintott mentions it too.]

Free food was again - mostly - a phenomenon of the capital. Other cities did have entertainment, but the local elite - that governed the smaller cities - payed for these. Most of the empire's budget went... to the army. [Starr (C.G.) The Roman Empire 27 B.C. – A.D. 476: a study in survival]

Again, correct, for the republic, which had A LOT of rebellions. Many in Sicily (104-101 f.e.), some in Italy. There were rebellions, but less.

I've mentioned this once before, but: there were two cities which caused much unrest: Rome and Alexandria (the two biggest cities). Both had forces stationed within them. [See, Davies (R.W.). “The Daily Life of the Roman soldier under the Principate.”] However, only the troops at Rome (praetorians) were considerable, but they were supposed to be a 'reserve' - Septimus Severus - in case of wanna-be-emperors.

Statistics? Also, the late empire was more of a feudal society. At the borders, you had soldier-peasants, bound to their land. Because of a lack of people, other farmers were bound to land as well, by rich landowners. Other parts of the empire were controlled by the foederati.

[If you want to check the - few - sources I've mentioned, I can look up the pages. That is, if you don't trust me. :p]