Sorcerer's Place has a nice interview with the Ossian Studios developers currently developing the first "adventure pack" for NWN 2: Mask of the Betrayer. Here's a portion:
SP: Will we need to create new characters to play MoW, or will it make sense to import and play with existing characters from NWN2 or MotB? What is the level cap going to be?
Kevin Smith: MoW is designed for a level eight character. If you start the game with a lower level character, you will be raised to eighth level automatically. If you don't plan on using any of the companions, then you might want to start the game with a slightly higher level character. On the other hand, characters who have completed the NWN2 official campaign or Mask of the Betrayer would definitely be too experienced for MoW (i.e., the game would become too easy), but there's no explicit level cap imposed at the start of the game.
Head to Sorcerer's Place to read the rest.