In order to post a job, you, as a user member must first create a company.

A user member can have multiple company, thus make sure you specify correct company in company field before submitting.

"Sponsored" company will be displayed in the most visible section of job browsing page.

It will have better chance catching attention of website user's members compared to "non-sponsored company"

No, job posts are still remained even after its expiration date.

It's necessary to keep these posts in case there are still some user's members interested in the position