Actually all the FreeCAD buzz and discussion happens on the forum at http://forum.freecadweb.org
If you want to get involved with freecad, I'd recommend you highly to create an account there and use it for discussions, this mailing list is, as you saw, very rarely used.
Checking new code in is something we usually do with git, there is a forum section for merge requests, and also a specific category for that on the tracker, but it's always good to discuss things before, as your ideas might already exist in some other form, or there might be someone else working on the same issue.

Yorik