2. Wind power works better for farmers and provide a smaller footprint. Drive on I-80 in Iowa on a clear night and you'll see the wind farms blink their red lights in the distance. Farmers can lease their land for wind turbines, and the generation companies take on the regulatory / capital / politcal risks, etc.
3. Farming is more or less free market based, and often farmers can let their grain sit in a silo until the price is optimal for them to sell. But for a given location, there's only one power company that you can use, and typically the power companies don't like people putting solar panels on the grid. In many states (like in Idaho) there's regulatory capture or weird politics preventing people putting solar panels up on their own land. (Again Idaho)
As a side note, agriculture uses up lots of water in deserts (more so than people), so it seems like in desert spaces like Idaho, solar would make a lot more sense than agriculture would. And we should move the agriculture to where the water naturally falls from the skies.