Hi SustainConsult,
I am part of the HEC MBA January Intake 2010, so here are some answers to your questions:
#Placement: they create recruitment opportunities, but it can more or less fit you, depending on your industry... and your French empathy. Whatever MBA program you choose, you still are the main actor of your life.
#Program Structure:
YES you can do an internship AND an exchange program. But be aware that they are just around 20 positions abroad for the Jan intake (vs around 70 for the September intake, even if they are more numerous they have more choices, like Wharton, and all the big names they claim to have). Moreover the selection process for exchanges is not cristal clear... this is the minimum I can say. It creates more frustrations than anything.
Beware also of the double degree option. These programs are "officially" opened for Jan Intake, but in reality you have no chance. Applications have to be submitted less than 2 months after you start the program, so they do not have any tool to evaluate you. No participant from the Jan intake was qualified to any of them.
#Networking possibilities: Jan intakes mix with September intakes, so this is not an issue. And YES we all share the electives Jan intake can attend.
I would definitely recommend you to wait for the September intake for other "insider" reasons: you will have the best professors (they don't teach in winter), you will have access to the full portfolio of electives (Jan intake are also frustrated by this), you will have access to more exchanges and double degree opportunities, and you will have more chances to be active in students clubs as soon as you arrive.
Last, if you want to do consulting, definitely go to Insead! If you want to do finance, go to LBS. For other matters, HEC is not so bad.