Avoid french universities at all cost. When french academic system was created, it took the sovietic system as a model. Therefore, french system is 100% public, 100% centralized, 100% bureaucratic.
I must add that french universities are non-selective by law (even the Sorbonne, even Strasbourg, and so on). Any student who wishes to apply must be accepted. Practically, it means that government is using the universities as a cheap way to control unemployement statistics : "ghost-students" (as we call them) are prodded toward university thanks to some social advantages and almost free tuitions. Therefore, roughly speaking, illiteracy level at undergrad level can be estimated around 30%. Most other students, though not illiterate, are completely unread. As an estimate, at undergrad level, I'd say that the BEST french universities can be compared with 3rd tier universities in the USA (1).
Plus, it's difficult to describe the state of disrepair, ruin, overall poverty in which french universities are sinking today. I'm too ashamed about my own country to give many examples : broken windows, dirt, graffitis everywhere, drugs dealers waiting at the door of your classroom, prostitution among students (a growing issue here), regular riots ... and so on. At my Alma mater, Strasbourg, when people used to ask the directions to the departement of pharmacology, we had to answer : "it's near the gipsy trailer park".
The Sorbonne's budget (the "great" Sorbonne), is roughly 1/30 of Princeton's budget... With the aggravating circumstance that it's entirely non-selective.
Follow this link, see the pics, they will give you a rough idea of the situation. The pics were taken in Strasbourg, during a recent set of riots, which are common occurence in France :
http://marcbloch2006.skyrock.com/However, if you want to teach in France, here are a few things.
I- Academic Ranks.
1) ATER (Assistant temporaire), PRAG (Professeur agrégé (2)) and Vacataire (litteraly : "fill-in") are untenured faculties.
2) "Maître de Conférence" is the first tenured rank.
3) Professeur des universités is the higher tenured rank. You have to be "Maître de Conférence" first.
II- Recruitment.
1) For untenured faculties, ATER and Vacataires are recruited directly by the universities, meaning you need contacts with the faculties members first. Don't expect miracles, these are cheap adjunct positions, mostly filled by recent Phd's, and sometimes ABD's.
2) As said in note, you need to be agrégé to become professeur agrégé. Logical. Get the exam first.
3) the Maître de conférence track, to get tenure, is something different. First, you need to send a scientific dossier to a national commission named CNU (Conseil National des Universités). The dossier usually contains your thesis, the defense report, your CV, list of publications, professionnal experience, etc. As said, it is almost necessary to put an agrégation in the package. This CNU, which gathers once per year, decides if you're worthy of tenure or not (3).
That does NOT mean you will be recruited. Next step, you'll have to be actually recruited by the university. Since the system is centralized, the ministery edicts by law the number of jobs available at each university. Once the university is allowed to recruit someone, it starts the process : advertise the job, read CV, conduct interviews, and so on.
III - Random remarks
1) as you can guess from my (very summarized, I assure you) explanations, tenure track takes a very long time. We're talking about YEARS of bureaucratic hell-on-earth here. That's France.
2) All the recruitment process is AT YOUR OWN EXPENSES. The CNU and the universities don't pay for the travel, the interviews, the hotels and the like. It's money from your own pocket.
3) since universities won't give a dime for recruitment process, inside candidacies (fake interviews with poor sods used as cameo), are much more common in France than in the USA. The faculties have no bad feelings about this, since they don't loose money. As a rule, it's always a good thing for the candidate to have connections in the target university, at the very least to know if the recruitment process is real or fake.
I must stop here because I don't have much time. Please pardon my english and the likely typos (can't reread myself. Must go).
As a conclusion, I'd strongly advise against any move to France. In fact, must of us are trying to get AWAY from it, in the hope to find a job in a much less bureaucratic country, like Cuba or North Korea. And I'm only slightly joking here.
---------------------
(1) in fact, what we call "universities" are not the best level of higher education in France. The best level is what we call "Classes préparatoires" (or, in short, "prépas") ... something like SLACS. Prestigious "Grandes Ecoles" (Ecole Normale Supérieure, Polytechnique, etc...) use this system, and NOT the run-on-the-mill university cursus.
(2) the "Agrégation" (no translation possible) is an entrance exam that leads to high-school teaching, "prépas" teaching and low-grade university teaching. It is organized by the ministery of education. It is very, very, very advised to get this exam if you want to teach in France. In humanities, especially, it's nearly impossible to get a job without it.
(3) as a sideline note, the CNU is composed like this : 1/3 of its members are named by the ministery, 2/3 are elected on Unions political lists. Imagine G.W Bush advisers choosing who can be tenured or not. I said "sovietic", didn't I ?