Committer: choosen by OCT, not TIP, or delegated by a package maintainer.
Bug czar: by volunteer. I doubt people will jump at the opportunity to do this work :)
Package Maintainer: self-nominated, approved by OCT
Site Editor: Volunteers. Possibly the OCT will delegate authority to grant permission to a Web Team of 2 or 3 people who can further delegate the maintainence of various parts of the site.