Funny. you are right that'd work. And it might win a Razzie for one of the worst movies of the year. But it would make a 2.5 hour movie that no one would like. You sound like a Hollywood executive.
It isn't A book, it is 7 books. Can you come up with a way to make The Lord of the Rings in 1 short movie? I'd love to hear that plot. Some short guys find a ring. They find some archery guys who shoot some troll looking guys. Then he trips on a stone and drops the ring into lava30 min sitcom.

I think a great actor for Eddie would be Shawn Reaves. He played Harrison, Tru's brother in Tru Calling. He has this kind of smirk and jokey attitude that I think would be perfect for the role. He's not a very well known actor but you should look him up.
http://www.imdb.com/board/20714188/

Interesting idea, but I can hear the howls of Dark Tower Fans already (including myself when you excise some of the best action bits of the series with dumping all the Susan Delgado/Big Coffin Hunters from the movie!)
Much rather see it as a tv series or series of mini-movies for television. Special effects have moved on (as well as the world) and now they could cope with those bits of the Tower saga with ease. A set of decent actors and it could work as a tv series.
I love the idea of dumping the whole of the first book. lol cutting out "The Man in Black fled across the desert, and the gunslinger followed" from the saga is quite possibly the most weird idea I have heard in ages. For a start off, its a classic image thats haunted Dark Tower fans for over 30 years! Its an opening line thats as immortal as "Saw a werewolf with a chinese menu in his hand" the film/tv series/cartoon NEEDS to start with that image. Even if they get NOTHING else right
That movie has warped my fragile little mind.

Well that is why it's a book and not a movie. Dont get your panties in a bunch, I was showing a way that it would be a reasonably length movie.