I answered two of those questions within days of the Aura one's launch a couple weeks back, and today I can answer the third.
A new review video by the Italian-language blog HDblog.it reveals that the Aura One does not have that internal microSD card slot.
This is going to disappoint potential Aura One owners who feel that the 8GB storage on the device simply is not enough. I can understand how they feel; the Aura One has an 7.8" screen which could be great for PDFs and comics - if not for the fact that PDFs will fill up that 8GB fast.
Then again, I have found (and other reviewers concur) that the Aura One is frustratingly slow at both opening a PDF and turning the page in PDFs, so I don't think the lack of storage is as much of a problem as it could be.