On world maps, don't factor in the x+31. I think you still do y-1, though.
Yes, but you need to do a -1 on the x axis on world as well.
The axes are zero-based meaning that tile (x, y) is really (x-1, y-1). However, non-world maps have 32 tiles of buffer to the left and right that stuff like blight can travel on (thus the +31).