Heat oven to 425°F. Place tortillas in single layer on 2 baking sheets. Coat with nonstick cooking spray. Flip tortillas over; coat with spray.
Bake in 425°F oven for 13 to 15 minutes or until lightly browned, flipping tortillas once. Transfer to wire rack. Sprinkle each with pinch of salt. Let cool completely.
Mix corn kernels, beans, chopped shrimp, jalapeno and red onion in large bowl. Halve avocado; remove pit. Scoop out flesh; cut into bite-size pieces. Gently stir into corn mixture.
Whisk together lime juice, cilantro, sugar, mayonnaise, salt, black pepper and hot-pepper sauce. Whisk in oil in thin stream until thick and well blended. Taste and adjust seasonings, if desired. Pour into corn mixture; stir gently to avoid smashing avocado.
Divide corn mixture onto baked tostadas, about 1/2 cup per tostada. Serve immediately.