a.are these kind of contracts which should be satisfied while message is sent from ep1 to ep2?You claimed to have read about all three. It doesn't seem so.
b.are these 3 files generated using automated tool or we have to write it from scratchThere are automated tools of course, writing them by hand would be very time consuming.
c.for example if i am going to send one xml file as message from ep1 to ep2, how many wsdl,xsd and xsl files required.thanksI think you have some more reading to do. You can send an XML file without using any of those. However, if you're talking about webservices, then WSDL and XSD become involved.