The Simplex stem shifters place the bike around 1973 or so; that assumes they are original equipment. I'd narrow it down to 73-75 on a semi-edumacated geuss. Maybe a bit later, but not much. The bike is roughly analagous to a UO/AO8, with cottered crank and no integral derailleur hanger. May have steel rims, too; I'd check with a magnet and switch them to alloy if you intend to ride this bike. As T-Mar said, some of the components may be replacements; the suntour front mechs were a common replacement for the Simplex ones, which reportedly have a tendency to break. I would wager the bike frame is straight guage steel. Nothing terrribly special, but the French did a nice job with keeping weight down on their frames; I was reading a thread on the fixie forum the other day on the weight of bikes, and was pleasantly surprised to realize my beat up UO8 fixie is actually lighter than most of the modern stuff. Even at 63cm.

The lone Gitane I have, which is either a Super Corsa or a Tour de France or some other higher end model (I haven't figured it out yet as all the decals are gone) has the serial number on the underside of the bottom bracket shell. I have no idea how to decipher these. I really need to investigate my gitane more and figure out just what it is. Right now I'm fascinated with the Bridgestone I just found, so it may be a while.