Use the “passwords” feature to check if one of yours is compromised. If it shows up, never ever reuse those credentials. They’ll be baked into thousands of botnets etc. and be forevermore part of automated break-in attempts until one randomly succeeds.
No + required. There are hundreds of companies offering aliases using their shared domain. You can also just generate a temporary email address if you don’t require any ongoing communication and the account is not super important.