American Express - BTA file - report RPR_AMEX_BTA_TO_FI

Dear SAP experts,

I am working on the integration of our BTA file into our SAP System. I find report RPR_AMEX_BTA_TO_FI and I am looking for clarification of the use of this program. I checked SAP Note 607109 regarding the settings to be done and so far I had no issue. I will use the option to integrate the file to the SAP Travel Management.

QUESTION 1 : as described in the here-under SAP Note, Reference-5 field is read as cost assignment. What if I want to use another custom Reference field to call my cost assignment? Is it flexible? Because Reference-04 is the only field we could use to store our WBS assignment that we transmit via the Travel Request as it is long enough to content the information.

QUESTION 2: what does exactly mean 'With Travel Management'? foers it create expense report and integrate the transaction inside automatically?

I noticed as well report RPRCCC_READ_BTA contains a clearing button. what does it mean?

Thanks a lot !