Even this post ist 1 year old, maybe this answer will help someone.
I faced the same problem. I had to export a 1.4 TB database but only 600 GB free space were available in the exportdirectory. So I had to move the splitted files during export.
I found out that you can move all files expect of part 01 (otherwise the export will crash). I guess it's a kind ...
You can use flashback info to get information about former DML activities of a given transaction.
The expectable details depends on wether supplemental logging is activated or not.
SELECT * FROM Flashback_Transaction_Query WHERE XID = :transaction_id;