Women are obligated in Birkat Hamazon. The Rambam holds either that it's Torah-level for women too, or a full rabbinic obligation. Either way: they must say it.
Question 2
Can a minor (who understands blessings) lead Birkat Hamazon for adults?
A minor who understands is rabbinically obligated. But fulfilling someone else's obligation requires being at the same or higher level of obligation — a minor can't do this for an adult.
Question 3
You ate a tiny piece of bread (less than a k'zayit). Must you say Birkat Hamazon?
The Torah says "eat and be satisfied and bless." Below a k'zayit, you didn't truly "eat" in the halachic sense — Birkat Hamazon is not triggered.
Question 4
Someone ate stolen bread. Are they obligated in Birkat Hamazon?
The obligation follows the eating, not the food's status. Even stolen food — once consumed — creates an obligation for Birkat Hamazon.
Question 5
Workers eating on the job — must they say full Birkat Hamazon?
Workers have abbreviated blessing options. The Sages recognized that workers on the clock can't stop for the full blessing — an abbreviated form was established for them.