Hi Ravi,
It is a long question that you are asking. A little resume:
ESR Level: you can check only your mappings from the test tab in the message mapping or the operation mapping.
ID: if you are using sender agreement,receiver determination, etc you can use the test tool of the ID. As far as i know, If you use an ICO object you can check the ID directly from the ID
Scenario level: It depends about your sender interface. For SOAP you can use WSNavigator o the Service Registry to test inside PI, from outside you can use an external tool like SOAP ui. For file/ftp sender you should to put a file in the sender path and to the check with the modo test (dont delete the file), for jdbc/jms you only can to set data in the sender systems to check, etc.
If you are going to work with determinate senders we can talk about them more specifically.
Regards.