Hi,
Is it possible create an archive or a page and set that all the user subscribed can see them?
Yes, this is possible with the « additional owner types add-on »
is it possible to create more space between the main menu and the plugin content?
Yes, you should add a custom CSS rule to your theme so that the WP Customer Area container gets pushed down. Please ask the theme developers how to do that, they are the ones who know how their theme CSS is crafted.
Regards,