There's not a lot of good documentation on those, though the functions are fairly obvious and easy to use.
Look for these functions in the source code:
add_post_meta
delete_post_meta
get_post_meta
update_post_meta
And examine them. They are fairly obvious. Basically you can add key->value pairs to any post and be able to pull it back later.
As for the editing hooks, I'm not entirely certain. You may just want to search through the source and find them to see where they are and what they do.
The best documentation on WordPress is WordPress itself. Whenever I want to know, I just go read the source code.