Hello shaase,
It appears your questions are mostly related to changing your Apple ID email address. Here's how you do that:
1. Go to https://appleid.apple.com and sign in.
2. In the Sign-In and Security section, choose Apple ID.
3. Enter the email address that you want to use as your Apple ID.
4. Choose Change Apple ID.
5. If you changed your Apple ID to a third-party email address, check your email for a verification code, then enter the code. Learn what to do if you didn't get the email. --> If you didn't receive your verification or reset email - Apple Support
6. If you use services like iCloud or Messages to share with friends and colleagues, sign in to those services with your updated Apple ID. --> What to do after you change your Apple ID or password - Apple Support
For more details, read the document: "Change your Apple ID" --> Change your Apple ID - Apple Support
You cannot change your primary account address if it is an iCloud address. You can use an alias for email. Add and manage email aliases for iCloud Mail on iCloud.com - Apple Support
If you really dislike your current iCloud address then your only option may be to create a different account, but that would entail losing everything associated with the old account. You are welcome, though, to see if Apple will change your iCloud email address thoguh I have never seen anybody mention being able to do that. To contact Apple, click here --> Choose your country or region - Official Apple Support
Select your country (also look for "other" regions), then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.
or:
Contact Apple for support and service by telephone --> Contact Apple for support and service - Apple Support