Crop yield + minimap (Farming Simulator 15)

Good day, comrades!
There is a yield parameter in the game, is it a parameter of the map or of the game itself? How can I change it for standard and new crops?
And will anyone tell you the real average figures for crop yields (ton or centner per hectare)? From what I found on average in Russia, and the numbers that are in the game, vary greatly.
And how are the mass and volume of crops implemented in the game? What parameters are used to register this whole thing?

And another question, do we have a mod - a map, a minimap image in the game - is it a separate file or a set of some layers, textures? Really replace it?