I have valley quail, so I don't know if your coturnix would have the same preferences. I've found that mine mostly leave alone lemongrass, Cleveland sage, butterfly bush, peppermint, Rosemary, lavender, and lemon verbena. They eat pretty much everything else, including mints. They love to eat small kale and cauliflower plants and all sorts of sprouts. I am trying to grow some basil, marigold, and kale outside of the aviary tall enough to survive them if I move it in, while allowing them to eat from it.
The ground in my aviary is covered in mulch, which appears to help them stay relatively clean even in rain, but they love to dig holes to bathe or cool off in the heat. They are impressive diggers and can make a hole large enough for them to lie in. I ended up lining the aviary with stones to discourage their digging against the walls. The outside of the aviary has a hardware cloth apron to hopefully prevent predators from digging in.
They love hiding places like boxes and plastic lids against the aviary wall, and brush piles when I've pruned my bushes. They roost at night (again, these are valley quail), so I covered the end where they sleep with a tarp to try to give them some protection from the elements. During the day, after feeding them, I sometimes also scatter birdseed to give them something to do during the day. They love to scratch for food.