Preheat oven to 325. Place tortilla wedges in single layer on 2 large baking sheets. Bake until crisp, turning once, about 30 minutes. Cool on baking sheet.
Spray small baking dish with oil spray. Add garlic; cover with foil. Bake until tender, about 30 minutes. Cool slightly. Peel garlic; mash in small bowl.
Heat small skillet over medium heat. Add cumin seeds; stir until fragrant, about 1 minute. Grind in spice grinder or in mortar with pestle. Add to garlic.
Bring large pot of water to boil. Add shrimp and lime peel and cook until shrimp are opaque, about 3 minutes. Drain shrimp and lime peel in fine strainer. Cool. Coarsely chop shrimp. Transfer shrimp and lime peel to bowl.
(Tortillas, garlic mixture and shrimp can be made 1 day ahead. Store tortillas in airtight containers at room temperature. Chill garlic mixture and shrimp separately.)
Add lime juice, yogurt, chopped cilantro, chili and garlic mixture to shrimp. Season with salt and pepper. Spoon atop tortilla chips and serve.