First I want to say, you have made a great guide.

I would to like to travel to Calcutta through the Underground Pathway from Holy Village. And the quester can better to attack than to defense. On my own experiences the defense seems not working against snakes. The damage is still same as the attack stand as the defense stand. Besides I see a lot members who are just lvl 35 fly away. So I advise that they can better have a HP of 500 or more. Or get a protector (earth user) who is faster than snakes. But don't use the stone wall, because it is useless. But the terrafication is the most useful.

The team would be minimal: 1 fire expert, 1 water expert, 1 earth expert and 1 quester (novice).
But it is better to be expert first, before you do this quest. Because Arrow Rain is not very impressive. The damage from the bow needs a lot ATK.
Even with my 450 ATK at level 82, I still can mostly make 300 damage on 1 mob. So low level players can only make too low damage.

O yeah, Water and earth, who helps the quester, can better have HP of 800+.