Can somebody explain the planet output types?

1) What determines the available output types?

     Bryia 3 is Gas Frozen. Why does it have food?

2) What does it mean if something contributes to an output type? What is the effect of the output type?

     In the picture below the Haroshem contribute to food. However, I can't see any bonus to the food output? (Bug?)

3) What can contribute to which output types?

    Does this mean it would be inefficent to put the Haroshem on Bryia 2 since it could not enable food contribution?

thanks