In a bowl, combine 2 tablespoons olive oil, minced garlic, lemon zest, oregano, salt, and pepper. Add the shrimp and toss to coat evenly. Let the shrimp marinate for 15 minutes while you prepare the couscous.
Bring the vegetable broth to a boil in a saucepan. Stir in the couscous, cover the pan, and remove it from the heat. Let the couscous sit for 5 minutes, then fluff it with a fork.
In a large mixing bowl, combine the cooked couscous with cherry tomatoes, cucumber, red onion, olives, and parsley. Drizzle with the remaining 1 tablespoon olive oil and half the lemon juice, then toss gently.
Thread the marinated shrimp onto the soaked wooden skewers. Preheat a grill or grill pan over medium-high heat.
Grill the shrimp skewers for 2 to 3 minutes per side until the shrimp turn pink and opaque. Remove them from the grill.
Finish the couscous salad with the remaining lemon juice and crumbled feta cheese. Serve the grilled shrimp skewers alongside the salad.