You're certainly right on the Planet Ocean front as I'm wearing the very same watch right now. However I'm astounded that Natasha can wear it so comfortably as it is one heavy piece of steel!! I'm haven't got a clue about the calibre reference; I bought mine in 2008 simply because I liked the watch!
Hehe. In 2008 they still had the 2500 caliber, which is a modded ETA one. The 8500 is in house, weights some more and has some other "tweaks", however some people do like the older one better.