(GRE Success! ) Queries regarding Computer Science Subject GRE

Hi,

I have done my BTech in Computer Engg.(2011) and wish to apply for Fall 2013. I had some queries regarding Subject GRE (Comp Sci).

1. Does Subject GRE add any weightage to your profile? I mean its generally prevalent that Universities ask for Subject GRE only if the candidate is of non-Computer Science background. So, does it help a computer science undergrad? 

2. What is the difficulty level of the test for Comp Sci compared to that of GATE?

3. Is it possible that one scores less in the test and doesn't want to send it to the universities?

4. Any online resources for preparation would be appreciated.

Thanks,
Prashant