How to add email address to a certificate

Hi

I generate a certificate using makecert.exe and using signtool.exe to sign my app. But in the file properties dialog box on digital signatures details the email field is "Not available". How can i add an email address to it (or and other extra information)? is it depend on certificate file (makecert) or signtool?

Also what is "Countersignatures" sectiton?

Another question:

When generating the certificate for code signing is it necessary to use passwords (requested by makecert & pvk2pfx tools)? or can i set them to none?

Thanks