A user can register as either an employer or a job seeker (you can also disable the job seeker login type from the JobRoller admin if you wish). The registration form is essentially the same as you can see from this screenshot:
http://i.imgur.com/MGStOyP.jpg
But the functionality of each login type is different.
1) There is no specific function for recording applications within the default theme, however you can set "BCC on all Apply Emails:" in the
JobRoller admin dashboard email settings which would give you some idea of this. The
FXtender Pro plugin available in the AppThemes marketplace does have this feature included in it along with other features not available in the default theme.
2) There are no settings to restrict the number of resumes which can be viewed under the resume subscription options, so this would require customization of the default theme on your part if you wanted to include this. You can see existing settings in the "resumes" tab of the JobRoller settings
here.
3) You can create
job plans which allow a certain number of jobs to be posted with payment required once, but they still have to create each listing separately.
4) Jobs aren't erased, but when it expires it can be sent back to draft mode and therefore will be unpublished. Users are notified by email of expiration and you can also allow job relisting if you wish. Thanks.