1. You have zero room for error if you're trying to hit high score so it's perfectly normal for ppl to double check what buttons they are about to press.
2. no idea
3. the fight isn't very tough to clear for experienced vets. OTOH it's extremely difficult to clear within 4 turns for a perfect score. You have TWO waves of mobs with over 1m hp each and the boss herself has 8~9m hp and is practically immune to debuffs. You figure out the numbers.