Just so that I understand: You're not allowing the players to create their own characters, you're changing the classes to your own versions, and you're planning this as the first of a series of modules for a campaign. In order:
1) I'd be interested in seeing how you work this out. While I wouldn't use this method for every campaign, it might work as a change of pace.
2) This won't work for me at all. I might run it as a one-off, but not build a campaign around it. I run 3E characters with my own house rules - even if I like your versions better, I'd have to learn the new classes, then house-rule them, then convince my players to change the classes they run in my campaign, sight unseen. Unless I run only the modules you publish, I'd have to adapt every other 3E/D20 module to your system, which I expect would be much more work than the other way around.
3) You intend this to be part of a series of modules to reveal the campaign world to the DM and players over time. Again, this won't work for me. I prefer to run homebrews anyway, but even if I didn't, you're expecting me as the DM to take a lot on faith. If the second or third module doesn't hold my interest, does the campaign end? If I don't like the direction you choose to take the campaign world, what are my options? Since you've already changed the classes, the most likely result I see is running one or at most two of the modules before going back to a more standard campaign.
I don't mean to be harsh - I'm intrigued by the character generation idea, and the rest of it might be an excellent one-off adventure, or something I can adapt to a regular campaign. But for the reasons above, I wouldn't be interested in this product as a series or campaign.
The more I think about it, this reminds me of the original Dragonlance modules - many people loved them, but I found that they gave me (as a player) too few choices. Things happened in the campaign series, regardless of my character's actions (or inaction). I felt like I was just along for the ride. By creating a setting that "introduces both the he GM and the players to the setting through discovery", I can't help feeling that same lack of control over the campaign, as both GM and player.