Reading for long periods on the Aura is just fine. (It is only when I compare it side by side to my other Kobos that I notice the screen is not quite as good). It has such a wonderful small size. It has 4 GB memory, and I don't even have a card in mine. No need for 64 GB, really! 32 GB is fine, if you need a huge card. Honestly, 2 GB would be fine also. ebooks simply don't take up a lot of space.
I would recommend a slim style case from ebay or Amazon.
This is the style I have and it is wonderful!
Look up the library management program called Calibre. It is awesome for using with your Kobo.
I've got almost 3000 ebooks on my Aura, and have a bit over half of the on board storage used. This does include many, many short stories, but as you can see, plenty of space thus far.