I read an interview which had Brian Lynch stating that we would see
* Charles Gunn
* Harmony Kendall
* Gwen Raiden
in the series.
I don't know how, but both Whedon and Lynch have confirmed that Wesley is going to be in it, too.
Apparently, Wesley was only killed because the series got abruptly canceled. He would have lived if Season 6 were picked up. So. . .yeah. Wes is coming back. Which, personally, I'm happy with as he was my favorite character outside of Angel himself.