Thanks +Detlev Zundel, sounds like pidgin would be the best starting place. Once OTR, audio, and video are up & running, then I might check into supporting all that inside emacs, if there were broad interest.
That's true, I guess it doesn't preview by default. If you want to see the other buffer immediately, you can try iflipb (install from Melpa). It gives you quick buffer switching with some visual aid, but hitting ctrl+g won't bring you back to the original buffer, unlike ido and helm.