Hi fanoi, on your question 2, I am pretty sure the Aura HD is not capable to take notes - so if you get a pen/stilus/anything you would only be able to use it to tap, swipe or select rows or words. But you cannot write notes in free hand. In fact, to do all of the above you can just use anything, including your finger.
For the excessive empty space, there is a patch that you can use to remove it, have a look at this thread:
https://www.mobileread.com/forums/sho...d.php?t=220171