1. 1969. If you just purchased yours, you should have a few years to go yet.
The rubber shocks age due to use, and smog. We never had a problem with the structure of the shell. The leather needed to be replaced from normal use, and our kids growing up using it as a Fort, rocking chair, and Olympic diving platform.
The replacement kit is foam and leather only. No more down inserts, but like new. Jacaranda ( Rosewood ) is not an option any more, so take care ( Peroba oil ) of it if you have it, or can find one.
2. Looking at the Chinese version, the bolts are Inox or stainless, and the stand support is of better construction. Solid. Leather looked good, but time will tell.
There is another more important aspect of the Eames chair; Music. Mine took me through many B&O system components over the years: Tube, Short wave, cassette, LP players, and two Reel-to-Reels. The good folks at Hermann Miller have been very helpful for minor parts over the years, just as Vitra is. Like an old Chris-Craft, this bit of wooden furniture should have died after about 12 years, but doesn't.
Hopefully our kids, and their children will continue to enjoy the tradition.