I have over 30 notes, papers, burned papers, pirate journals and books in my "Usable Items" category. Can I get rid of these after I read them? Will I need any of these further into the game for any reason?
Yes, you can get rid of them. Anything that is still required by a quest should be under "Quest Items" (and will generally be moved after you read it).
You can do whatever you want with those items. Throw them away if you want or sell them.
If you've already read the important quest books or notes or papers they will be removed from the Quest Items slot of the inventory.
Why would you want to throw them away?
- They weigh barely anything
- If you forget about a valuable quest detail you can always check back and read it.
I still believe CD Projekt RED will add storage to the game so I advise to hold on to those books and papers. They don't weigh anything.
Once the developers add storage just store them there.