Can a monster, similar to a hero, move 2 spaces, execute another action, like attack, or open a door, and move 2 spaces again?
Yes. From p. 8 of the rulebook:
"Monsters follow the same movement rules as heroes when moving except that monsters cannot suffer fatigue to receive additional movement points."
In case you're still not convinced, p. 3 of the FAQ specifically calls out "When a large monster interrupts its movement to perform an action" as part of a question referring to large monster movement.