For the trailer it may be a timing thing. Russia's holiday is later than the US and Europe's (they tend to use the orthodox calendar), so their big holiday movie weekend is three weeks after ours. There aren't any big movies coming out this weekend, or net weekend, so Marvel has to wait on the US trailer release.
I do wonder what the reasoning behind the spread out release dates is, though, from an industry perspective--is it because of the holidays, because of logistics, tax breaks, or (as I've heard before) a way to keep movie piracy under control.
I don't have a problem with it, really, I'm just intrigued about how some seemingly illogical choices turn out to be driven by rather logical rationale (like why spiral staircases in castles tend to spiral clockwise, etc)