How to implement an E-commerce solution for a jobboard?
This can be easily done with the Recruiter Distribution and Ubercart or Commerce.

If you are not using the recruiter distribution you can used the Profile2 to created to ask  


  - Checkboxes (for terms and conditions) - Document upload (CV,
  picture etc) - Other basic details (name etc)


For the Terms and conditions you can used the Site Disclaimer module. 

You need to created a role that allows them to register to the website and created a profile. After that you can add a button to Upgrade their to another role which would give the user the ability to see or do more stuff in your website. 

You can follow this tutorial to learn how to upgrade a role with Ubercart. How to Configure Drupal 7 and Ubercart to Sell User Roles