Elin Forest is whole Victoria Island?

That's exactly what the deal with Stone Bug is, I wouldn't rule out more of those types down the road.

Hell, that one in particular could have been around(or possibly its descendants) to dig the caves.

Would it be interesting if they used some of the monsters from Masteria for this time?

The idea of Versal MomMush(or would that be mushdad?) being the same as the one for back then would be cool.