Is it possible to customize the labels of the Project Reports Menu?

Not yet. See the related issue: MPIR-35

How to exclude SCM access info?

See the SCM report documentation.

How to hide developer/contributor email addresses?

You could use services such as reCAPTCHA Mailhide. In this case, just replace email by the given URL, for instance: ... foo http://mailhide.recaptcha.net/d?k=01ebFB9eM2hZL-T96IpUgRmA==&c=AI-pouLFNTr5xMTBVDaj8iKeIFI5dy9Wj5cxSY0Nuhw= ... ... ... ]]>

How to use developer/contributor time zone?

According the Maven XSD, the developer/contributor time zone fields are string so you could use a time zone as a number in the range -12 to +14 or a valid time zone id like "America/Montreal" (UTC-05:00) or "Europe/Paris" (UTC+01:00).

Is it possible to customize the reports rendering?

Not yet, but patches are always welcome! You could only customize the texts in the reports.