Will Elites be playable like they were in Halo 2/3 in the Anniversary playlists? I for one hope so, and that they are given the same health and stats as the Spartans for true SvE Classic gametypes!
Halo Anniversary’s multiplayer is just some new reach playlists setup to emulate halo 1 multiplayer and some new reach maps.
So the elites work like they do in Reach, because your actually playing reach multiplayer.
Hope this helps clear things up! :]
Have a read of the pinned Guide/FAQ, but yes, ChrisOfTheDead summed it up. The multiplayer component of the game is purely Halo Reach maps, with modified game types to emulate Halo CE.