I'm totally with you on that. At first I was bizarrely distracted by it - I mean, come on. It's a freaking moose - but then it grew on me, and now I'm actually really glad that they put it in. Because it does make Thranduil stand out a bit more from the rest of the Elven realms, which is exactly how it should be - the glimpses we get of Mirkwood in The Hobbit make it look totally different from Loth Lorien and Imladris - not just through setting but through the people as well.

I like to think that he would, and that he would privately be seriously smug about the whole thing. A hoard that huge and a Silmaril on top?

They didn't mention it outright. It was a very sideways reference (that I could be making up entirely because this is totally my head-canon) when they mentioned Thror becoming obsessed with gold and sickness spreading, because that was what the Dwarven Rings did (if they had an affect at all).