I came on here to purchase it and it isn't in production anymore, but the expansions are?
I thought that was weird so maybe I was just reading it wrong.
None of the game's expansions are in production anymore. It's possible that not all of them have sold out on the web store yet (I haven't checked), but everything is out of print as of last November or so.
The only new and upcoming material for Descent is the Second Edition core box, which will entirely independent of the first edition.
The only actual question I had about the game is this. Does the Overlord actually have a fun job, or is he just a rulebook that lets the players have fun by helping them win?
The Overlord can be played either way. By design, he is intended to be a legitimate opponent with as much chance of winning as the heroes have. Some groups find this jarring to what they expected the game to be, however, (ie: they thought the heroes would always - or at least almost always - win) and those people often choose to play a more lenient game.
In short, there's nothing stopping the Overlord from throwing the game in the heroes' favour if he wants to, but that's not how the game was designed to be played. The Overlord is a player like any other, and he is bound to adhere to the rules just as any hero player would be.