Alright. Let's just say I have uploaded a work. And it isn't validated yet. How comes it is available in iGloo before that? Also, if someone downloads the work which isn't validated yet, and then some team member validates it and it's available in the Gallery, is the download number reseted or Gallery "remembers" the download number?

  the 2 first uploads (not yet validated) are available in your iGloo (immediatly)
  then, you'll have to wait for some of the members of the Team to validate/refuse your works to upload some more.
  DL number is automatically reported, of course.

Can I set iGloo not to have those unvalidated works?

No,

We assume that you don't post a creation, if you don't want it into your iGloo !