Cook orzo in large pot of boiling salted water until just tender, about 10 minutes. Drain. Rinse with cold water to cool; drain well. Transfer to large bowl. Add green onions, feta cheese, chopped dill, lemon juice and oil; mix well. Cook shrimp in large pot of boiling salted water until pink and just cooked through, about 2 minutes. Drain. Rinse with cold water to cool; drain well. Mix into salad. Season to taste with salt and pepper. (Can be prepared 8 hours ahead. Cover and refrigerate.) Mix cucumber pieces and 3/4 of cherry tomatoes into salad. Transfer to clean large bowl. Arrange cucumber slices and remaining cherry tomato halves around edge of bowl. Garnish salad with dill sprigs and serve. Serves 20. Bon Appetit June 1994