Hello,
Regarding point n° 1 : hard to say. You may try to debug event handler EH_ONITEMPICK (view ICCMP_INBOX/InboxResultView). Your message is displayed because of an exception.
Can you check which instruction leads to the exception (line "CATCH cx_root INTO lr_ex.").
Regarding point 2 : hitting the "Interact" button leads to the automatic identification of the business partner, depending on the item type selected in the inbox. This will also create an interaction record upon confirmation of the identification of the business partner.
Hope this helps.
Best regards,
Sylvain