Bring a large pot of water to a boil. In a small pot, steep the saffron in the stock over medium heat while you make the sauce.
In a large saucepan, heat 2 tablespoons EVOO, two turns of the pan, over medium-high heat. Add the leek, fennel, onion, carrot, celery, thyme, bay leaf, crushed red pepper and half the garlic; season with salt and pepper. Cover and cook, stirring occasionally, until the vegetables soften, 8-10 minutes. Add 1/2 cup wine and simmer for 1 minute. Add the tomatoes and bring to a bubble. Add the saffron stock and let the sauce simmer while you cook the seafood.
In a large, deep skillet with a tight-fitting lid, heat the remaining 2 tablespoons EVOO, two turns of the pan, over medium-high. Add the clams, shrimp, squid and the remaining garlic; season. Cover and cook until the clams open, shaking the pan occasionally, 5-7 minutes.
When the water comes to a boil, salt it, add the pasta and cook until al dente. Drain, reserving 1 cup of the starchy cooking water. Return the pasta to the pot.
Add the remaining 1/2 cup wine and the lobster to the seafood mixture; douse with the lemon juice. Toss the seafood and half the sauce into the pasta, adding reserved starchy cooking water, as needed, if dry.
Transfer the pasta to bowls. Top with a little more sauce and pass the remaining sauce at the table.