1. Preheat grill to high heat.
2. Cook pasta according to package directions, omitting salt and fat. Drain pasta.
3. Drizzle 1 tablespoon oil evenly over fish; sprinkle with 1/4 teaspoon salt and 1/4 teaspoon pepper. Grill fish 5 minutes on each side or until desired degree of doneness. Remove from grill; let stand 5 minutes. Break into 3/4-inch pieces.
4. Combine 1 tablespoon oil, squash, and zucchini in a large bowl; toss to coat. Sprinkle evenly with 1/4 teaspoon salt and 1/4 teaspoon pepper. Place vegetables, cut sides down, on grill rack; grill 3 minutes or until lightly charred and just tender. Cool slightly. Cut into 1-inch lengths.
5. Cut 4 squash blossoms into 1/4-inch-wide strips. Combine blossom strips, pasta, fish, squash, zucchini, remaining 1 tablespoon oil, remaining 1/4 teaspoon salt, remaining 1/4 teaspoon pepper, herbs, and juice in a large bowl; toss to coat. Top with feta; garnish with remaining squash blossoms.