1. in the first scenario, shall I need to create actual IR objects since i dont have IR objects right now due to directly pass through flat file?If yes how the structure compatible with the flat file payload since I tried but failed?
Yes you should create IR objects and then use a java mapping. The java mapping should be able to create attachment using the incoming input payload (flatfile) and then pass some pass static values for webservice structure (second PI exposed webservice, I hope just one field structure is enough 
)
Follow my earlier answer as well for other ASMA related settings
Regards,
Praveen Gujjeti
