Bring a large pot of lightly salted water to a boil. Cook pasta according to package directions, adding shrimp and peas for the last 3 minutes of cooking time. Drain in a colander. Rinse with cold water to cool quickly.
Meanwhile, whisk together mayonnaise, mustard, lemon zest, lemon juice, dill, smoked paprika, and salt in a large bowl.
Add pasta mixture, roasted red peppers, carrot, celery, and red onion. Toss to combine. Serve immediately or chill, covered up to 4 hours. Garnish with additional dill.