I’d absolutely love to have a proper plugin for this. I haven’t been able to read all posts in detail but just a short note about user fields:
You can already have any number of fields for users via the API in the same way you can add fields for pages:
$user->update(array(
'somecustomfield' => 'with a custom value'
));
They are just not editable so far in the panel, which is already on my list. If you need anything else I will try my best to give it a higher priority for the next updates when it fits.