Wordpress plugin for multi-user, multi-profile website

I want to create a upwork.com like website in Wordpress called geeksboston.com and I do NOT know what type of plugin/extension I should use. Basically my idea for the site is something like this:

• I as administrator need to have full control over users/geeks accounts (enable, disable, delete, etc)
• Everything should be free of charge for both "geek" and "user".
• Automatic registration process with email validation and captcha.
• If you are a "geek" you can create your profile entering your experience, resumes, certificates, etc.
• Regular users are not required to register, but can navigate through out the website, look for/contact geeks, etc. But to contract/rate a geek, this user must be registered.

I am new in Wordpress but heard that it can do great stuff. So any clue?

via Chebli Mohamed