Webhook V1 Clarifications

I realize there are 2 webhook versions v1 and v2. I feel v1 is suitable for my usecase because it send events regarding all objects(all files and folders) happening in user’s account. I would like to know the answers to following questions:

1. What are the different types of account that can be held at Box?
2. I created a custom app and tried webhook v1 triggers and it seems to work fine, but from https://developer.box.com/guides/webhooks/manage/manually/ , I do not understand this statement “By default V1 webhooks only work for users that are developers of the application and have access to the app in the developer console. To enable these webhooks for all users, please contact support.” Can you please clarify these for me?
3. Does webhook v1 triggers events for all user who make some changes in the account?