I think you could probably do this without code too.
You obviously would need one large text box and then a repeating node with 10 rows of 65 characters each.
I would have an rowID field and then the small text field.
So on the main view they add their text blob.
When finished they select a button.
You set field actions to populate the repeating nodes.
Use substring function to take the first 65 characters and set them to the text where id = 1
Then the next 65 to row 2 and etc.
On the export view have a repeating table control that displays the 10 records and that will be what is exported to Excel. Whatever is visible on the view when export is selected.
I would send the data straight from Infopath to the DB if possible and skip the Excel. Web services are the way to go.