You should use the Get Users endpoint Reference | Twitch Developers as that will return both the profile image and description.
You don’t need to, that’s an optional scope and is only needed if you wish to know their email address. Any OAuth token will work, be it a user access token (you don’t need any scopes at all) or if you’re making a request on your server then an App Access Token will work. If you use a User token then you don’t need to provide id or login params as it can just get the user id from the token itself, but if you use an App token then you must provide one of those params.