Q: Savety about iCloud

I am not sure you have this correct. My iCloud user name (or Apple ID) is my e-mail address. There is a separate iCloud password. My e-mail site has my e-mail address as the user name but it also has a separate password. So, for someone to get into either account, they would need to know your individual passwords.

If you are concerned about security of iCloud you may want to consider turning on the following: Two-factor authentication for Apple ID - Apple Support

This would be true only if your Apple ID is an @icloud.com, @mac.com or @me.com address.

If they can hack your Apple ID and take control of it, they also change the password for your email so you are locked out of it as well.

A rescue email will get you notice of the hack, but by then it's likely too late.

Adding 2 Factor Authentication to your Apple ID can prevent this. Without your trusted device, your password can't be changed.