I read a WiKi article that the Hand might somehow be related to the TS race. But that might very well be just be more of a wild guess than a fact. I'd also have liked to see more of both, but sadly LotR flopped so badly...
As for the the whole beyond the rim thingy: Well, what else could the old races have done but to ride into the sunset and head for new frontiers after the younger races proved to be self sufficient and they grew tired of their childish squables?
And even fully grown ups like Vorlons and Shadows are entitled to feel like kids again when in the presence of a parent. And even more so when he/she raises a finger and tells them they did something wrong. So I don't have a problem with how this arc was ended.
And Lorien being somewhat like "God" I wouldn't say. He does not seek the admiration and worship of his creations. I always thought the Ori in Stargate:SG-1 are more fitting in that respect. 
Serenity was a theatrical release, Shadwohal. Even here in Germany, where the Firefly series didn't even make it to the local TV broadcast, it hit the theatres. Joss Whedon gave a damn about the revenue in this case. He wanted to give the loyal fans kind of a satisfactory ending to the story after the series was cancelled.
Agreed that it's business, and that WB would of course have a great interest in making as much money from the movie as possible. So THEY would want to make it attractive to more people than just the existing fanbase. But trust me: JMS will not have WB's suits dictating what he movie has to be like. He'd rather drop it just the way he did the TMoS project and the Lost Tales project.
Maybe he finds a golden middle way to achieve both. Satisfying the fans and attracting a new audience. Who knows? 