Using a as card on a uno seems the best approach. You can buy shields that add SD capability with other services such as Ethernet or a LCD - advantage is that it plugs right in with a tight fit, or get an SD card and run a few wires. You can create the text files on your PC - ensure its pure ASCII text, save that on the ad card with a simple numbering scheme sur as story0.txt, story1.txt, story2.txt,...strory9.txt and use SD card library to open file for reading, read characters and do your motor things until end of file, then close the file and move to next one