Managing a member database with wordpress

I would like to make a website for an organisation which has a number of members. We would like to use wordpress to store the members’ details, and therefore allow them to change them themselves. The users would have a number of fields available to them, such as email, home address, phone etc., while from the admin backend there would be additional fields such as ‘Paid’. How can this be done?

it’s much more than a blog, more of a CMS, and the site owner wishes to have everything in one place rather than having different applications

Is there a reason why you want to use WordPress for that? Its not so much a user management tool as it is a blog app IMO.