I believe Project Raptor (SQL Developer) was mentioned as early as Oracle Open World 2005. If you chain backward through our OTN download pages, the earliest archive still listed is a patch to release 1.1 (May 2007), which may have been before your time if I read your other posts correctly. The development team is geographically diverse.
In terms of feedback:
1. Bug reporting can either go through Oracle Support or this forum.
2. Developers most likely will check the forum more frequently just after a new release. Dialog does occur.
3. New features / enhancement requests should made on the SQL Developer Exchange.
4. Direct e-mail contact may be offered, usually when dealing with some difficult-to-reproduce bug.
5. Some developers and product managers have blogs, which can be another opportunity for dialog.