The movement roll for each Adventurer is 1D6 (movement die) plus 4 squares, this result corresponds to the number of attached squares (sharing a common edge) that the character can move. (page 14 of the rulebook)
For each new move, the movement roll is rerolled.
The move is interrupted if the character performs another basic action (a free action does not interrupt the move). (page 16 of the rulebook)
Monsters, on the other hand, move the number of squares indicated on their card.
The orientation of the miniature is chosen by the player at the end of the move. Moreover, once during your phase and only if you have not moved, you can change the orientation of your miniature for free.
Note: The Archer’s Nimble ability allows him to move diagonally.