As per the features outlined on the plugin page, yes those who apply for jobs will become registered users (whereas by default this does not happen), and there is capability with the plugin for resumes to be uploaded. JobRoller already allows resumes to be viewed online by the employer as you can see on the
JobRoller demo, but when applying for jobs, the job seeker needs to attach a resume separately. With the FXtender plugin, it will allow the job seeker to attach a resume they have already uploaded to their dashboard.
If you have more specific questions about the plugin itself you are welcome to ask the plugin developer directly on the comments section of the
plugin page. Thanks.