Paella with Asparagus and Sugar Snap Peas

5 cups (about) low- salt chicken broth, divided

1 pound uncooked large shrimp , peeled, deveined, tails left intact, shells reserved

3/4 cup dry white wine

1/2 teaspoon crumbled saffron threads

1/4 cup olive oil

2 Spanish chorizo sausage links (6 ounces), casings removed

2 1/2 cups chopped onion s

3 large garlic cloves, finely chopped

1 large tomato (12 to 13 ounces), halved, seeded, cut into 3/4-inch cubes

1/3 cup drained roasted canned Piquillo pepper s or drained roasted red peppers from jar, coarsely chopped

2 teaspoons Pimentón de la Vera (hot Spanish smoked paprika ) or hot Hungarian paprika

1 teaspoon salt

2 1/2 cups Spanish Bomba rice, Italian arborio rice, or medium-grain white rice (about 17 ounces)

18 small littleneck clam s (about 1 1/4 pounds), scrubbed

24 mussel s, scrubbed, debearded

5 ounces sugar snap peas, trimmed

Lemon wedges