1) Sim
2) "Moving Nazgûl and Minions
When the Shadow player uses a Character Action Die result to move his Characters, each Nazgûl (including the Witchking) can be moved to any region on the game board with a single move. One, some, or all Nazgûl can be moved this way using a single Character Action Die result.
The only restriction is that the Nazgûl can never move this way into a region that contains a Stronghold controlled by the Free Peoples player, unless that Stronghold is besieged by a Shadow Army."
Minha interpretação: Como a fortaleza sitiada ainda não é controlada pelos Povos Livres, então pode se mover de/para esta fortaleza.