Yes, the holotapes are the key, they unlock the various stages of the quest, as well as Victoria Watts speaking to you. And there's more holotapes than those mentioned. There's also one in Big Town and in the office of the repair ghoul in Underworld, I forget his name. I suspect there's other scattered around as well, possibly with the doctor in Tenpenny Towers. I think you need something like 3 holotapes to fully unlock the quest, maybe 4. Victoria Watts will approach you as soon as you have 3 of them at least. And it doesn't matter where you get the first holotape, as soon as you have one of them, the other NPCs involved will have a dialogue option that unlocks new options for the quest.