Haha, this is authentic recipe of chirashi-zushi, though anago (eel-like fish) and shrimp are not always used.
The pink powder is called denbu - sweet fish-meat floss made of cod, as you correctly guessed. Pink one is called sakura-denbu because of its colour. (It is tinged with food colouring.)
It's not made from dried cod, but from raw fish. Sometimes tai (sea bream) is used instead of cod. Boil the fish meat, drain and squeeze, wash out any oil in water, drain and squeeze agian, ground it with mortar and pestle, and cook in a pan with a little sake, sugar, salt, drying it with low heat.
It is often used in chirashi-zushi, even in Tokyo. I'm from Tokyo and it was my favourite when I was small because it's very sweet.