X4 setup

Hey, I should be receiving my x4 soon and I had a couple questions about setup. First is max sd card size and format(ntfs, fat32, etc.). Also as far as sorting books, can groups of books be placed in separate folders or do they all need to be in the same folder or root of the sd card. One thing I was thinking of doing is loading up different groups of books on different sd cards, but I also wanted the x4 to keep my place in each book between cards. I don't know if switching cards will wipe the placeholder in the books or if those markers are stored on the cards, if that make sense...