Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
There was no direct answer to the question of which duck was more delicious. The search results mentioned that male and female ducks had their own characteristics and tastes, suitable for people with different tastes. The meat of the male duck was slightly rough and chewy, suitable for people who liked chewiness, while the meat of the female duck was more tender and delicious, suitable for people who liked soft texture. In addition, there were also differences in nutritional composition between male and female ducks. Male ducks were more nutritious and suitable for middle-aged or elderly people, while female ducks were suitable for people with weak bodies, such as pregnant women who were in confinement. Therefore, the taste of the mandarin duck depended on one's taste preference and health.
It's hard to pinpoint exactly where Gojo is at any given time in the manga. His whereabouts change as the story progresses and different scenarios unfold. It could be in a supernatural realm, a mission site, or interacting with other characters.