Mathematics at Parisian universities

[Redsummers]

Is anybody here knowledgeable about the system in Parisian universities? –I have a couple (or maybe a bit more) of questions which I don't seem to get clear answers from the internet, rather mixed ones.

The first one is concerning Paris 6 (UPMC) and Paris 7 (Diderot). I know they both are in the latin quartier... or should I say were? Is Paris Diderot (math faculty) now in the 13e arrodinssement?
Last time I was in Paris, I visited the Jussieu Campus... now my question is, as far as the Jussieu Campus 'corresponds' to UPMC, it is also home of most scientists from Diderot, right? That said, can one take classes from both universities distinctively of where the student is enrolled?
When visiting the Jussieu campus I noticed that they were constructing (or reforming) stuff in there, is this still going on? Doesn't this affect the classes at UPMC?
Also, does someone, per chance, know how many students are enrolled each year in the mathematics masters (M1) in UPMC and/or Diderot?

Alright, last question is concerning the 'machinery' of the ENS. I see that normaliens usually graduate (also) from other universities in Paris and then they just seem to be 'members' of the ENS during that period. I know the ENS also offers courses, but why do students need to be enrolled in another university? –I am not sure whether I understand the true functioning of the ENS.

Also... last questions (really now), but not academically-related: about accomodation, would you think that CROUS is the easiest way to get accomodation for students in Paris? –Also, I have seen in some websites that 'chambres' alone are offered for under 200€, does that seem legit? http://www.adele.org/public/residence/residence-universitaire-concordia-paris.php Do you have any idea (in case you have experienced it yourself) when should one apply for accomodation? (always considering enrollment to a university in Paris by Fall 2012)Thanks a lot for reading! Any help is appreciated!

 

[Mépris]

Try asking the same questions on futura sciences (don't remember the URL; look it up) and forum.prepas.org - the latter should have more than enough people who can speak for the ENS and I think they'd be nice enough to talk about the Parisian universities as well. Just change the wording a little, for the only relevant forum for this type of thread I've seen there is "Questions Generale sur les Ecoles".

I can imagine that since there are a number of universities within proximity, there is no need for each to hold its own set of advanced courses. For the L3, M1 and M2 (senior year of BS and the two years of the master), it's *probable* that there aren't too many students in the classes. Say, the faculty of Paris 6 (haha!) is focused on geometry and that of Paris 7 on analysis, then it makes sense why students take different lectures at different "branches". Maybe it's just an ENS thing (it would appear that their physics program is set up in a similar way) or perhaps all master's degrees at French universities are inter-departmental.

Note that this is just an educated guess...and as such, it could be completely untrue but it does seem reasonable to me.