Difference between apple ID and Apple email

Mail service is just one of the features iCloud presents. So, your Apple ID is like your identity in Apple ecosystem and lets you to utilize Apple related services. Mail is just one of them. If your Apple ID ends with "@me", it doesn't matter. Some finds it "obsolete" and some finds it "cool". Just act as you wish. It wouldn't harm you in anyway. You can add alias to your Apple ID if you're concerned.

Just check this out:

https://support.apple.com/guide/icloud/use-email-aliases-mm6b1a490a/icloud

No, it doesn't matter.

See if anything in Section 3 helps.

Apple ID - Password/Security Questions verification e-mail not received.