Before starting, figure out, does this get sun all day, morning, evening, which way does it face? What part of washington? Is it hot and dry there or rainy? This will tell what you can grow and how to maintain it.
You'll probably be taking out a lot of the gravel. Maybe it's just a layer on top they tried to 'mulch' with? Get gloves on and pull out the vines and grass.
You will add compost or garden soil to refill.
Ant and spiders are not particularly interested in your plants. I think they just like the rocky terrain.
