Do birds require ritual slaughter the same as animals?

When in halacha are we able to apply the concept/principle of rubo k'kulo (the majority of something is seen as the entirety of it) and when does it not apply?

When a woman gets married and she comes from a Sephardic home, if her husband is Ashkenazi, is she required to change her Customs to those of her husband's?

Are soldiers allowed to eat non-kosher food they find in houses when they are behind enemy lines?

Was the permission to eat meat upon entering Eretz Yisrael a concession to desire or a mitzvah opportunity to enjoy the pleasures of the world?

What are the rules when a prohibited activity/melacha is performed on Shabbat regarding use or enjoyment of that product?e.g. a person cooks on Shabbat, are they allowed to eat that food or not during or after Shabbat? What about other people?

Are avocados that become ripe only after Shabbat beguins considered permissible or prohibited?

Is a shochet allowed to wear glasses while performing shechita?

What internal organs of an animal if any, does a slaughterer have to check for kosher status?

Is all milk kosher to drink?