1.JobRoller pulls jobs from Indeed.com and
Simplyhired.com.
2.JobRoller by default places first the user submitted
featured jobs, then the jobs from indeed/simplyhired and then the regural/non featured user submitted jobs.I saw threads in the forum where users changed the order easily this order.
3.Yes you can leave empty the 'Job Listing Fee' field and allow free posting of jobs, there is no fee for posting a resume.
4.I can see in the back end that JobRoller uses two different pages for submitting a job and editing a job.So my guess is that it uses two different ids.
5.I am sorry but there is no trial period for any of the themes.