In a bowl, soak noodles in water until softened. Drain well.
In a pot over medium heat, bring about 6 cups of water to a boil. Add noodles and cook for about 5 to 7 minutes or until cooked but firm to bite. Drain well and set aside.
In a pot over medium heat, bring about 2 cups water to a boil. Add cabbage and cook for about 30 to 35 seconds or until tender yet crisp. With a slotted spoon, remove from pot and submerge into a bowl of iced water until cooled. Drain well and set aside.
In a pot over medium heat, bring about 1 cup to a boil. Add squid and cook for about 1 to 2 minutes. Using a slotted spoon, remove from the pot and set aside.
In a pan over medium heat, add pork belly and cook, stirring occasionally, until lightly browned and crisp. Remove from pan and drain on paper towels.
Peel shrimp, leaving tail intact. Reserve shrimp heads.
In a pot over medium heat, bring 1 cup water to a boil. Add shrimp and cook for about 1 to 2 minutes or until color changes. With a slotted spoon, remove shrimp from pot and set aside. Reserve liquid.
In a pan over medium heat, add 1 tablespoon oil. Add tinapa flakes and cook, stirring regularly, for about 1 to 2 minutes or until lightly browned and heated through. Remove from pan and set aside.
With a knife, coarsely chop reserved shrimp heads. In a pot over medium heat, combine shrimp heads and 5 cups water. Bring to a boil, skimming any foam that rises to top. Lower heat and simmer for about 10 minutes to extract flavor. Using a fine-mesh strainer, strain liquid and discard shrimp solids.
In a small bowl, combine 1/4 cup of the shrimp stock and annatto powder. Stir well until annatto powder is dissolved and water has changed to orange color.
In a large saucepot over medium heat, combine shrimp stock (about 4 cups from boiling the shrimp heads and about 1 cup reserved from boiling shrimp), fish sauce, and annatto water.
Add shrimp base and stir until dissolved. Bring to a boil.
In a small bowl, combine cornstarch and 1/4 cup water. Stir until smooth. Whisking vigorously, slowly add the cornstarch slurry to shrimp stock and continue to cook for about 5 minutes or until slightly thickened.
Add crab fat and stir until combined. Season with salt and pepper to taste.
In a large bowl, combine noodles, cabbage, sauce, chicharon and tinapa flakes. Gently toss and then transfer to serving plate.
Top with hard boiled eggs, shrimp, pork, toasted garlic bits and green onions. Serve with calamansi wedges.