Meta PM interview questions

You are the PM of the "share" feature(which people use to share on feed, as a private message etc.). How would you measure success of this feature? What metrics would you use and why? Out of the ones you have mentioned, which is the most important and why? Followup questions: 1) Your team has implemented a change in the "share" and released it for A/B testing, where you realized that there is increase of 20% usage of the feature. would you decide to release it? 2) You have recently released the new feature, and you were informed by all local sites (Facebook sites in each country) that the usage has indeed increased by 20%, but the overall global data shows only 5% increase. How is this possible?

Execution question: You are just appointed as a product manager for Facebook Live; what would you do? (What would be your north star metric, what would you build next for Facebook Live?)