I don't wish to have "email" as a compulsory field in the comments form, how do I make it non-compulsory?

In blog config, in the comments section, you can choose "allow anonymous comments", I believe that takes care of it.

But if I wish to make Name a compulsory field and Email not compulsory? Anything else I can do?

May I ask why you don't want to make email required?

If it's for spam prevention, you could require it, but just not display it with the posted comments.