My file first started crashing when I tried to soft-return following an em-dash, en-dash, or hyphen. For a while I worked around this by soft-returning on the line below, typing in the text from above, and backspacing the line above (all to help with typesetting the rag).
I had diagnositics run on my machine at the Genius Bar where they replaced my battery and ran first aid, etc.
Software-wise, I've since tried deleting preferences, etc, in the library. I looked to delete the application support file but didn't find one. I also tried opening the file on a second laptop and it still crashed when I did the items above (returns, copy/paste). I tried exporting to an .inx to clean up the file. However, when I open it (Untitled) and try to save it as an .indd to keep working, the software freezes.