WordPress user profile page uses the administration interface, and its user registration / login page is not part of the theme. I would like to
- change it into the custom theme of my site
- customize login / registration page, hopefully with a custom form, and captcha
- remove the top bar when the user is logged on
- retain this top bar functionality, and administration interface access for administrators and contributors (because I'm using 'Debug Bar' plugin, which is a part of the top bar)
- for the rest of regular users, just hide the dashboard (technically make it inaccessible even if URL is entered), and use the profile page with site theme.
How do I achieve this? I'd like to use filters/hooks and maybe create a custom plugin. I prefer not to change the code of WordPress itself.