Registration: username as email, duplicated fields, avatar, visibility issue

Hello!
In the registration form that gets created through the shortcode

[mb_user_profile_register id="meta-box-id" label_submit="Register" confirmation="Your account has been created successfully."]

I have the following issues:

1. I want to use the e-mail address as username, and not allow the user to pick a username.

2. I have a default-fields group that lists first name, last name and email address and this way the email address field is duplicated in the top section and in the following section of the form.

3. I have a custom avatar and it’s setup as a “single image” but I do not want the user to access the media manager. This should behave like the “image” field but with “multiple” attribute set to false.

4. Once I’m logged in and I access the registration page, I see the form. I should see a message like in the login form: “you are already logged in”.

Thanks!
Mauro.