Hi lens, thanks for finding our forum and sharing your thoughts!
Our own documentation is definitely geared towards the people implementing the editor in MODX. One of the tricky parts of providing a full end-user documentation (aside from the obvious time and priorities questions), is that we encourage users to tweak the experience for their users depending on the skills and needs.
I’m not even going into the Imperavi docs, as those are about Redactor.js II 1.0, while Redactor for MODX 2.0 uses Redactor.js I 10.2, for which documentation has been demoted to a pdf download 
Some time ago @sottwell send us a draft of an editors guide she made for Redactor. If she says it’s okay I would be happy to post that here, though that was written before we released 2.0 so (at least the copy I have) is a little bit outdated.
To try and answer your specific questions…
To leave block level tags (ol, ul, blockquote, pre etc), you will need to hit enter/return twice. The first time it will create a new line within the block, but the second time it will break out of it. For inline tags you would use the arrows. For tables you can reach the end of the line with the arrow tags, followed by enter.
With advanced attributes you get the ability to enter IDs on certain elements (images and links) that can be used as anchors, with the linkAnchor exposing a way to look to an anchor.
Hope that helps. If you’re still being troubled by mysteries and quirks from the upgrade to 2.0, be sure to let us know here on the forum or via support@modmore.com, we would be glad to help figure those out.