It's pretty much ready to go out of the box. It has twenty or so plot hooks to possibly dole out to characters one way or another. It also has reasons for each faction to send adventurers there to check things out. The town that functions as a "home base" of sorts has two levels of clues/rumors/plot hooks depending on whether the party is level one or level 3/4. I, personally, adapted the plot hooks to be a series of dreams that I emailed my players a week before our first session. Each character had an individualized dream customized to their character. I guess I did a pretty good job personalizing them, as the players didn't really want to compare dreams at our first session. ( The Barbarian laughed about having a "wet dream" as he woke covered in sea water from a dream of the ship he grew up on being wracked by a storm apparently directed by a man covered in barnacles, hoisting a trident above his head. )
As I said, eight pages of ideas for converting to other worlds, including Eberron. I haven't but skimmed that section, as I'm a pretty big fan of the Forgotten Realms. ( In fact, I did a lot of work to convert Return to the Temple of Elemental Evil to Faerun, back in the day. I know, sacrilege to some. )
It's not exactly a mega dungeon. While the places are all connected, they shouldn't be completed as if they are. Travelling back to town fairly often should be something that gets done. There are a good number of side quests presented, some related to the main quest, but some completely divorced from it. There are also a number of scenarios detailing the responses from the cults, as the heroes start taking down parts of the temples. ( They will at some point begin lashing out at the local towns and communities. ) As far as establishing a base, there are a number of places where it would make total sense to do so. One thing that gets mentioned in passing a couple of times, but I don't see directly addressed is the possible need to guard some of the locations as they get cleared out. These would be good places to establish a base of operations.