Hello!
OK, since this is stuff you'll need for the certification, I'll try to explain a bit:
WSIT is a joint effort of Sun and Microsoft to enable web services and web service clients developed in Java and developed using WCF (Windows Communication Foundation) to talk to each other. A little bit like the WS-I BasicProfile, but for WSIT there are also code supplied so, theoretically,
you should be able to create a client using C# and WCF that accesses a Java web service and not have to bother about the underlying details.
Metro is the Java web services stack (libraries) that GlassFish uses. Metro also implements the WSIT standard.
WS-RM is a standard, WS-Reliable Messaging, that can help you to ensure that messages sent to a web service really gets there. It is also possible to configure WS-Reliable Messaging so that the order of the messages sent are preserved when they reach the web service and you can also specify whether you want a message to be delivered exactly once or if at least once (with possible duplicate message(s)) is good enough.
Since I am a skeptic
I want to try things out myself, before I believe. So far, when trying to have a WCF web service client talk to a Java web service, I have encountered a lot of problems. However, it is too early to say whether the problem is me or WSIT/WCF.
Please do not hesitate to ask if there is anything unclear!
Best regards!