GTA Online is crap on PSN, it doesn't work yet, hope it is fixed soon..
Anyway I did some research and I found out these GTA IV characters will also include in V:
[spoiler]- Rocco (Ballad of Gay Tony), you have to kill him.
- UL Paper , killing him is optional
- Karen / Michelle , killing her is optional
- Terry & Clay (forgot to mention those) , you have to kill them.[/spoiler]