I haven't seen the extended scenes because I bought the Hobbit on Amazon for streaming instead of the DVD. Worth buying the DVD for instead?

Oh wow, I want to see Elrond's face! Hee!

That's a very good point about holding territory without a ring. He's got only small magic and bows to hold off the giant spiders et al. So yeah. I wonder if Thranduil knows where the rings are? Or guesses?