You can register online or by phone or by mail. The detailed information about registering for the GRE can be found at www.yocket.in
Extracurriculars are always an add-on to your profile. Any achievements at the state or national and international level are considered important. Working for social causes such as for an NGO or charity trusts on a regular basis
Universities have more or less the same application process, yet it's the little differences that create doubts and confusion. Post them here and get discussing about it now. From safe, moderate and ambitious universities, it's almost an art to figure what's best to apply.