Add some meta data to post inserted using wp_insert_post function

Should I retrieve the most recent post id ofter the post is inserted and use the id or there is some simpler method?

That’s what I’d do, except that wp_insert post will return the “ID of the post if the post is successfully added to the database” so you don’t have to retrieve the ID. You already have it. Just catch the ID like so $myinsertedpostID = wp_insert_post($whatever); and check that it isn’t ‘0’.