According to CD Projekt RED, no Items or Equipment carries over from The Witcher 2 save file.
Only decisions carry over.
Because they made the games for the consoles and they don't have previous save files they allowed for the user to choose the decisions of past games.
So basically there are no differences from importing the save and simulating one by choosing the decisions.
Since you don't quite remember what you did in those Witcher 2 save files I would recommend to you the simulation of one by choosing the decisions in-game, and you will be more aware of the decisions in-game.
No, not all decisions carry over. Only really important ones for the story. The decisions that are made in the Q&A session are:
- Did you kill Aryan?
- Did you choose Yorveth or Roche?
- If you picked Yorveth you'll 2 choices: did you save Triss or break the curse of Saskia? If you picked Roche did you save Triss or help him save Anais?
- Did you help Sile in the Megascope or not?
- Did you let Letho go or not?
There are some decisions that you make in the Witcher 2 for example: (SPOILER ALERT)
If you killed King Henselt
This decision is not mentioned in the Q&A Session and there are other decisions that are not mentioned.