True to words, sometimes it's difficult to go back and read every Word to word probably after a long text, but however I do try my best to run through them, sometimes in between writing and when I'm done.
About the tags I do that after prove reading make sure I check to ensure it posted in the right community, with correct tags, I literally do a lot of checks before finally hitting the publish button.
I don't think I've ever had a reason to delete any post before
It pays to proof read slowly and carefully as it helps people present their posts well. Whatever works for you is the way to go though.