Bitlocker's main job is to protect against physical threats. Theft, drive removal, etc.
Encrypting your main computer is probably the most important. Passwords are basically useless if someone has physical access to machine that isn't encrypted. Windows 7 is EOL at the end of the year. Win 7 Ultimate does have bitlocker protection but I would just implement Bitlocker when you switch to Windows 10/Server 2016/2019.
You have to keep the password/key in a safe place. There is no way to get your data back if you lose the key. It's transparent to the network.