The role of Hawke and the DA2 party in DA4.

One could argue that Varric told her. TN also gave me personally the impression that there is a fair number of people that have been informed beyond just the Inquisition's Inner Circle of party members+advisers+Charter.

Varric probably told the enitety of the Hanged Man.

This is what the epilogue said:
After the events at the Winter Palace, elves left the Inquisition under mysterious circumstances, as did elven servants across Thedas. None could say where they went, but those who believed the Inquisitor's story about Fen'Harel wondered just how large the Dread Wolf's forces were... and what the ancient elven rebel had planned

Clearly more people were told than just the inner circle because I hardly think they would have doubted the Inquisitor's word. However, of those beyond the inner circle clearly it was something not readily believed. Clearly they couldn't miss elves disappearing and may well have thought the idea of some crazy elf claiming to be a god was believable but the rest of it? I think quite a few people would find that a rather hard truth to swallow, particularly since the Chantry has been pushing their version of history down everyone's throat for the last 900 years and that doesn't have a place in it for elves or their heretical myths. Likewise, would the majority of Tevinter Altus be willing to credit that not only their conquest of Arlathan wasn't against the might of the elven empire but a poor remnant of it but that a survivor of the ancient elves had credited himself with creating the Veil.

Still, I agree with others that those connected with Varric would likely be told and that would include Merrill. It has also been apparent from Tevinter Nights that the agents of Solas have been going around for a number of years trying to recruit likely additions to their number, so Merrill may have been targeted for an approach but had been forewarned by Varric and so did not fall for their propaganda.

Various groups have also had run-ins with either agents of Fen'Harel or the Dread Wolf himself and so an awareness of him would have spread through gossip. Even if people didn't believe his claim to be an elven god, the evidence is there that he does have command of many spirits of the Fade and is capable of the old Dreamer ability to slay his enemies in their sleep, so it is likely that more astute mages will be warding themselves from his influence.

Whilst knowledge of Fen'Harel could cause a backlash against elves, wise rulers would do better to actively cultivate their loyalty. If the original message was passed on that all modern races were going to die if his plans reach fruition, that might well give the city elves pause for thought provided their situation wasn't so dire it made no difference either way. I would have thought any Dalish would heed their own legends and remember that Fen'Harel is known as a trickster who cannot be trusted. Seeing as his own story confirmed he was responsible for shutting away the elven gods, they would be well advised to treat any friendly approaches by his agents with caution.

Agree with the part about the former PCs.
Disagree about Varric making sense, since last we saw he is running a city.

I really can't see any reason why we need a character from a previous game with the next one set up north, well away from our previous haunts, so you wouldn't expect to see any former companions there, apart from Dorian because they made sure he was sent back to his homeland. It is now so long since the previous game most casual players will have all but forgotten characters from the other games anyway, whilst they will mean nothing to people totally new to the setting.

And yet there he is again, narrating the trailer and promising that "I've got your back". I find it ironic to think that had the Exalted March not been cancelled, Varric wouldn't be in a position to return because he would be dead. It is amazing how he could transform from "expendable character we can kill off" to "indispensable character you can't manage without."

You know I never really understood why Cassandra needed to bring him to the Conclave.   Why did he need to tell his story in person?   Doesn't the Divine trust the word of her own right hand?  As for the alternative story that the Divine was a fan of his work and wanted to meet him personally.   Well, surely that would have been more appropriate when she was back in Val Royeaux and an easier journey for him from Kirkwall, rather than dragging him up to Haven during such an important set of negotiations?    So I hope they come up with a better reason to involve him if he does turn up in Tevinter.

That is what I mean. It would be better to have a clean slate of entirely new characters but Dorian at least makes sense given the focus of the action is likely going to be Tevinter and the fact that he always goes back there no matter what and is always made a Magister regardless of how you left things with his father, would seem to suggest they intend using him.

I don't believe that Isabella had connections with Tevinter, apart from Maevaris/Varric which was only tenuous. Whilst they had the Crow characters sailing off back home in Tevinter Nights, I can only assume this was before the Qunari invaded because after that I would have thought the seaways would have been very dangerous indeed, particularly for those trying to sail round to and from Antiva. So Isabella would need a very strong incentive to risk her ship again. Still, I do concede that she has a better connection with people in Tevinter than most other characters from the previous games. The other one with the strongest connection from DA2 is, of course, Fenris but unlike Isabella he can be dead,, so notwithstanding his appearance in the comic series, I wouldn't expect to see him there except possibly in a cameo role, with an alternative placeholder character if he didn't survive and the plot requires it.