This is abit more of a discussion than a direct answer. Do you need the double quotes in the middle of the values in the final data (in the DB)? The fact that you have a large amount of data to munge doesn't present any problems at all.
The "" thing is what Oracle does for quotes inside strings. I think whatever built that file attempted to escape the quote sequence. This is the string manual for MySQL. Either of these is valid::
select "hel""lo", "\"hello";
I would tend to do the editing separately to the import, so it easier/faster to see if things worked. If your text file is less than 10MB, it shouldn't take more than a minute to update it via sed
.
sed -e 's/\\//' foo.csv
From your comments, you can set the escape char to be something other than '\'.
ESCAPED BY 'char'
This means the loader should verbatim add the values. If it gets too complicated, if you base64() the data before you insert it, this will stop any tools from breaking the UTf8 sequences.