This seems very interesting! The flavor bonus is brilliant.

 I was wondering, shouldn't the main spell casting ability of the druid be WIS? 
Now the class gets +2 WIS, but it's INT-based.

And shouldn't spell DC be 10 + INT?

Found this today, and we'll be playing this pretty soon when introducing new people.

Sorry for the late reply.  

shouldn't the main spell casting ability of the druid be WIS?

I don't remember if that was intentional, but it would certainly make sense to change it to WIS.  Or to simply give Druids INT +2, WIS + 1.  

And shouldn't spell DC be 10 + INT?

Yes, it seems you're right!