Hey Jason -
It's been a while since you asked this question, and I bet you've figured this out on your own. If not, let me give you some closure.
1. No - The extract creation / publishing must happen through Desktop.
2. Yes. Starting in Server 7.0, you'd select the workbook in the portal (via it's checkbox), click the blue Scheduled Tasks menu item, then in the Tasks page choose to add your Full/Incremental refresh.