The purpose of curation is to add value to the content and reach more users.

You are perfectly right . Curation also involves discouraging spread of spam or plagiarised content and may even involve downvoting the content.

It means every post is active after publishing from 5 minutes to 6 days 12 hours and then after that post expires

Yes that's perfect explanation of a voting window. We know that before 5 minutes reverse auction takes place and after 6 days and 12 hours linear discounting takes place.

Good luck .