Guide says...

1) Letting Aryan live, or killing him in 2, affects your interactions with a woman named Molly during Main Quest: Broken Flowers (page 99).

If Arjan is alive (or you have no save game) from Witcher 2, the Baroness
introduces you to the general, but there is no need-you've already met (it is none other than Morvran Voorhis). You ask
about Molly and the Baroness says her maid-servant is currently at the home of
her dear friend, Patricia Vegelbud.

If Arjan is dead in Witcher 2---the Baroness recognizes you as the man who
murdered her son, and treats you with cool detachment and derision. You ask
about Molly; who profited from Arjan's death as she is no longer a maid, having
married the Baroness's nephew. They are currently at the home of the Baroness's
dear friend Patricia Vegelbud.

2, 3) The path of Roche or lorveth

This only effects a very small conversation choice during Main Quest: Get Junior,
when you visit Roche's camp for the first time.

4) Sile de Tansarville

If you allowed her to die (PC save game) or tell Voorhis this (PC, consoles without
save game), she does not appear during Main Quest: The Great Escape (page 181).

If Sile de Tancarville survived during Witcher 2, she is also with Margarita; she pleads with Yennefer for a quick death. You can choose to administer this, or leave Yennefer to do it instead.

5) Letho

Answer any questions and mention Letho is still alive, and Secondary Quest:
Ghosts of the Past, becomes active later (see page 91 ).

Mention that Letho is dead, or ignore the conversation, and Secondary Quest:
Ghosts of the Past cannot be accessed.

Refer to a youtube video for Letho cameo for details, and you are all set!

P.S. Henselt dies either way, sparing him in 2 or not. The swine he is, though, MUST die from Roche. Have at him, no mercy!

I think we shouldn't write Iorveth (or Saskia for that matter) off just yet, remember we still have two expansions ahead!

Correct. The devs themselves actually "spoiled" somewhere, concerning the expansions, "return of old, loved characters" in them.

Keeping fingers crossed...

Although, in my playthrough, she did not make it alive. Mercykiller ftw, especially since in Roche path you cannot "cure" her.

Except we are told by Geralt at the start in White Orchid, that Radovid has taken Aedirn.

An NPC apparently mentions that Iorveth was killed by a bunch of arrows. Haven't seen that bit of dialogue myself, but a few different people have brought it up, so it seems legitimate.

So what, Nilfgaard has occupied Temeria (by that logic Roche, Ves, Thaler shouldn't be in the game either).

If you find any screenshots or videos of that, please link them (in theory it also could be propaganda, here's hoping)!?

Who would the remnants of their army be fighting, The Northern Kingdoms (Radavid), The Nilgaardians or both?

I think the same as few Scoia'tael examples in Velen, almost like bandits more or less fighting everyone (fighting for surival).

Roche wants to assassinate Radovid. And spoiler really, but this is for the greater good. In the end, Temeria gains independence if Nilfgaard tramples Redania for good. Or else prepare for Radovid tyrannical monarchy and terrible, savage, nonhuman and witch hunts. Sigismund is bad too, because he pulls off something like the USSR in the northern kingdoms.