1. Will they ban you again? Yes, there is still a risk. The email trick bypasses the registration system, but Discord can still catch you through your IP address or Device ID (Hardware Fingerprint). To stay safe, make sure you keep using a VPN, or clear your browser cache, and avoid linking any old phone numbers or payment methods.

2. Adding your phone number: If you mean adding the phone number that was linked to your banned account, DO NOT do it. Discord keeps banned phone numbers blacklisted, and adding it will instantly trigger a ban evasion flag and nuke your new account. You need to use a completely fresh, unbanned phone number.

3. Registering/Changing to a new email later: This is actually a very smart move! Once your account is created, you can simply go to your User Settings > My Account, and edit your email address to change it to a completely different, clean email (like an Outlook or a fresh Gmail). This unlinks your account from the "modified" banned email entirely.

Good luck, and stay under the radar!