Hi Sri,
I had issues with 0SRM_TD_PO_ACC but not for 0SRM_TD_PO. I simply initiated the delta for 0SRM_TD_PO and this has also initiated the delta for 0SRM_TD_PO_ACC (but I also initiated the delta for 0SRM_TD_PO_ACC seperately).
I can't help further to your question re Shopping cart and PO number as I don't have any experience in classic scenario.
Thanks,
Emir