Preheat barbecue to high heat (450-500F) for 10 minutes.
For the shrimp marinade: In a small bowl, combine olive oil, garlic, lemon zest and juice, ½ tsp of salt and ¼ tsp pepper.
Skewer shrimp alternating head to tail and push them together so they're snug (this will keep them moist). Pat dry with a paper towel on both sides. Brush shrimp on each side with a generous portion of marinade.
Skewer tomatoes, brush with olive oil and sprinkle with remaining salt and pepper.
Over direct high heat on an oiled grill, grill shrimp and tomatoes for 2 minutes per side. Close barbecue lid other than to flip. Remove from heat and allow to cool slightly.
In a small bowl, combine ingredients for dressing. In a separate bowl, combine orzo and feta. Add ⅔ of salad dressing to orzo, reserving the remainder to drizzle over completed salad.
Arrange greens on a platter, top with orzo mixture, grilled tomatoes and shrimp. Drizzle with remaining dressing and garnish with additional feta and lemon wedges if desired.