hi Carioca,
not sure about the localization question, but shy of what lists out of the menus, i'd think there shouldn't be any real problem between the "english" version and "non-english" OS...

... actions are a little more "literal" when it comes to menu listings, but since i don't have access to non-english environment i can't really test it out...

as for the activation, yes adobe's activation is targeted to the specific computer and communication between system and Adobe must be established either via internet or phone call. You need to make sure you "deactivate" Photoshop if you move it to another system or plan on reformating the hard-drive...

hopfully others from outside of the U.S. can give you more feedback regarding your first question.

retrocity