Alright, so I started a game in NG+ mode, but I'm wondering, how do your Witcher 2 choices actually work?

I select New Game, difficulty and tutorial options.
I'm then prompted to either import a Witcher 2 save or simulate. I chose to import my Witcher 2 save.
I choose New Game + On
It then tells me "To start New Game +, you must first choose a save made after completing the standard version of the game."
So then I have to choose "Something Ends, Something Begins".

Something got hosed, because I got all the way to the House of Reardon quest in NG+, and Letho didn't appear, even though he did during my first playthrough. Now I'm wondering if the Witcher 3 save does something to erase choosing the Witcher 2 save.

Did anyone have any problems with this after they started NG+? Should you just choose "Simulate Witcher 2 save" to be sure? Maybe it's just bugged?

Yes save game import from W2 works.

Starting a NG+ is just like normal new game only with an extra save to load for the game to be in NG+ mode.

I don't remember the order but its just like newgame>Difficulty>W2save>W3savecompetionautosaveNG+ (manual saves dont work just like they dont for the W2import) The W2 import just like the W3 save import are optional

*AUTOSAVES* is the key (might be checkpoint save, same difference anyway)

You know that save the game does for you inside Kaer Morhen soon as the ending/credits etc are done.

So if the saves you use aren't autosaves, you're screwed?

Yeah I for example cant restart a NG+ now that im on my NG+ due to the missing required savegame.
You have to go to a manual save and do the last boss battle bit (I cant remember its been 3 months, i think its ciri-scene+boatdude fight+ final boss fight, pretty sure you cant save between those)
Its annoying but it shouldnt take too long really.

Nevermind. I just used a signpost to teleport to another location to create an autosave that way. I'm going to try and start another NG+ with this and see what happens.

yeah you could try some sidequest as well to see if its a checkpoint thats required as well