Have been following this thread with some interest as a user who uses Data Merge all of the time. Very rarely do I come across this issue, but when I do it is normally when the job is in a hurry.
I've downloaded the csv from the google file and noted the same thing the OP had noticed, and that was the quotes appearing as the OP had stated in part 18 of this thread.
My solution was to go into Textwrangler on a Mac and save the file as the following:
Then, went back into InDesign, selected "Select Data Source", and (making sure that "Show Import Options" is checked ON) selected the new database. A dialog box should now appear with these options:
and voila! The data should go from bad to good!
