Am I following the rules?

Hi all, I'm new to the site, and I want to make sure I don't break the rules.  I play correspondence chess, and my understanding of the rules is that using reference material for openings is allowed.  So if my opponent plays some opening I've never seen, I can look it up online and see what the main line is.  I can't use analysis engines, but I can use previously written material.  Is that right?  Thanks!

Correct. You can use any static reference material: books, opening databases etc, but can't use an engine (or endgame tablebases) or otherwise ask for advice on a specific position.

You can also move the pieces around in between moves (you probably already knew that) but I think it's worth playing CC games like over-the-board games - really helps to keep your calculating ability strong

Ok, thanks.  Out of curiosity, why are references ok for openings, but not for endgames?

References are fine for endgames, as long as they are static. Endgame tablebases give moves based on the board position. If you got into a bishop endgame and wanted to look it up in Silman's endgame course for example, that is completely fine.