Maps reset every 5 minutes as long as there's no players on the specified map. Monsters flagged as "boss_monster" on the spawn scripts (Usually MVPs) will not be affected by this. This means that their HP/etc will remain the same after a map resets.
As for ranged resists, as I recall, physical skills from mobs are ranged from 4 cells or above, regardless of the skills' natural range. For example: Pneuma will protect you from a Cecil Damon's skills if you're 4 cells from the mob. Less than that, safety wall will save you from the mobs' skills.
Yup, it's the island aspect of bifrost that makes the Parus map so challenging. I don't remember if the map allows for Intimidate either, and I'm leaning towards "no, it doesn't allow it."