3) At no point in Revenge of the Sith does Obi-Wan hear Anakin referred to as "Darth Vader". He does see brief footage of Anakin's attack on the Jedi Temple but that's it.
4) Yoda hears Palpatine refer to him as "Darth Vader" but we do not see him pass that name on to Obi-Wan.
Obi-Wan hears Palpatine refer to Anakin as "Lord Vader" in the Jedi Temple recording and then Yoda refers to him as "Darth Vader" later in the same scene.
http://ca.youtube.com/watch?v=Yt4G6RPrO64