In regards to whether he's spirit bending or not, as bad as Tumblr can be, there was a really good post on there explaining how what Amon did in comparison to the Lion Turtle and Aang.. was completely not spiritbending, but yeah.. maybe just a better form of chi blocking based on his 'henchmen' doing the same. I'm thinking it's all a show, and he's not spiritbending someone's bending away for good, but using it as a scare tactic, knowing the big gathering would attract the Avatar. So he gets her to come there, scares her with the spiritbending (along with the others there), then lets her escape so she can spread the word, considering everyone will listen to the Avatar. Sends mass panic for him without him getting his hands dirty. Plus he still looks like a good guy who wants peace considering he 'removed bending' away from the Triad leaders.