I'm pretty excited by these sets as well, but was hoping for some better photos before commenting. IMO it's fair game to comment on these here, though, since this is promotional material that was given out at a Toys R Us, so I call that an official release.
Spoilers follow, though I suppose you've already been spoiled if you're reading this.
-Originally it seemed from various clues that movie 1 would end around the point of the barrel ride. Now it seems that after they made the decision to make three movies that they will cut movie 1 off somewhere between the warg attack and the spiders. This may be as a cliff-hanger, e.g. with the dwarves up the trees, or maybe at a resting spot like Beorn's house.
-I see three types of orcs (four if you count the Goblin King), similar to the different figs we got for the Moria orcs vs the Uruk Hai of Isengard. Presumably we'll get some different breakdown of various orc clans or even sub-species in the movies.
-On Legolas and Tauriel fighting the spiders: Yes, the movies will have some significant changes from the books. Part of this will be the expansion of hints from the books about the attack of the White Council on the Necromancer (who they find to be Sauron). In the Hobbit book this is simply an excuse for Gandalf to disappear from the company from the point they meet Beorn until he comes back at the Mountain, and Tolkien refers to it as Gandalf's business 'away down south'. It's only at the Council of Elrond and in the appendices to the Lord of the Rings (and more in some of the Unfinished Tales) that we find out what was going on. Anyway, all indications are that there will be a secondary story line where we see more of this. In addition, there will be changes that I will just try to be generous and say come as a result of making a more movie-friendly story. Think of this in the terms that a non-book audience would be expecting:
Bilbo and company are going to be traveling through Mirkwood and will meet up with elves there.
Hey, we already know about Legolas, one of those Mirkwood elves. Given that we know from the Lord of the Rings movies that elves are an extremely long-lived bunch, and that Legolas is the son of the king of the Mirkwood elves, he's surely going to be there.
Guys know Legolas as a kick-butt fighter. Girls think he's dreamy (here I'm ducking to avoid the bricks that Blue and Plums are lobbing at me). So he's SURELY going to have a major role.
Given all that, Jackson is pretty much painted into a corner by the expectations of a movie audience to give Legolas some major screen time, not just hanging out at the elvish picnic that Thorin interrupts. Yes, he'll surely be doing some of his major sled-surfing, Mumak-climbing studly fighting in movie 3 (or, I suppose, the elves of Mirkwood could send a contingent along to the Battle of Dol Guldur suggested above, and he could be in that), but once you've got Orlando Bloom on board for the earlier movies you're going to have to give him some action.
That said, as you implied, Bilbo's fight against the spiders is one of the key moments in his character development, so I hope that the elf-spider fighting (which, btw, is also suggested by some other movie stills that have been released as part of promotional material) does not completely supplant the hobbit-spider fighting.
-Back to other thoughts, I'm also pretty excited by finally seeing the leaf element in fall colors. I hope we see more of that from LEGO.
-While I'm not thrilled about the design of the Goblin King battle set, it looks like an awesome parts pack for a castle builder - lots of greys and browns, slopes, weapons, etc. The Barrel Escape set is another good parts pack for brown and tan and castle-relevant pieces.