Is the pacific northwest home to a temperate rainforest where over 300 centimeters of rain falls yearly?

Yes, you are right, it is over three hundred (300) centimeters

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.