I would convert the file to FileMaker by just dropping the file on the FileMaker Pro icon. Then clean your data, get rid of bad data (duplicates etc) and then sort records
After that go to your solution and import the file and you will get them in your sorted order and without bad data
ditto. I always import (to a new file or new table) as temporary data. I might even set up relationship(s) to show where duplicates might occur.
this KB article may also help:
(see links at bottom, too!)