- A client, which sends commands. The client runs on your development machine. You can invoke a client from a command-line terminal by issuing an adb command.
- Don't forget to disable it once you've done all the things you need. Don't use it constantly. This module allows you to run adb daemon from root user.
- if somebody wants to root their phone, they'd use adb and run various commands, so no you don't need root to use adb.