Can I still keep my 3rd-party email as my Apple ID if I sign up for iCloud Mail?

Here is what I am looking to do, or at least thinking about. I created my Apple ID forever ago with a third party email provider, and since then, Apple released iCloud Mail so you can have an @iCloud.com email address. I thought about setting it up, but if I did, would that new email address take over as my primary email address for my Apple ID? (For example: When you sign up for Gmail, your Google ID is replaced with your Gmail email address.)

If that does happen, is there a way to setup all emails from Apple to still go to my third party email? (For example: iCloud/iTunes receipt emails to still be sent to whatever@anotherProvider.com versus whatever@icloud.com)

If not, is there a procedure to set it to the third party email? Or does it not switch to begin?

Unfortunately, the primary email address page doesn't really make it clear what happens after setup. (Reference: Create a primary email address for iCloud Mail - Apple Support). I'd like to try iCloud Mail out, but I don't want it to impact my Apple ID right now, since I am not sure if I want to switch to it quite yet.

Thank you, in advance, for the clarification.