Anything can be taken from you at any time. Google can also just delete your account for no obvious reason. I guess that a domain can also be taken away but maybe not that easy. At least you can switch mail providers easily without having to change all your accounts that are based on your mail address.
Yes, but the likelihood of them giving your email address to another person is low. Not so if somebody gets my domain out from under me.
Google can just block your account for no obvious reason and ask for KYC, which could easily leave you without access to your email for a week.
Hope that's not your case, but seeing how irresponsible Google is in its actions, I couldn't tolerate such risks.