Add extra info to byline or remove on individual posts

Hi there,

I’m trying to do one of two things–

Add text to the beginning of the entry-meta for the posted info, so ideally, “My message” | by Author | Post Date — Is there any way to do that?

If not, how can I remove that section all together for a single post? So far all I’ve been able to find is how to remove it theme-wide which is something I don’t want to do.

Thanks in advance for any replies!