I've been using the Free Google Voice from the beginning and have incoming calls forwarded to multiple cell phones on different mobile networks, including to my Voip home phones. In fact, I don't recall most of my assigned phone numbers as I only give out my Google Voice no.
I even set my outgoing caller id on my home Voip to display my Google Voice no. instead of my actual phone number.
But the real power of Google Voice is in its call management capabilities. Which can allow specific callers to ring through. Send those you don't really want to talk with automatically to voice mail. Or send telemarketers to a phone disconnect message.
As for email, you can easily create multiple alias or alternate email addresses in Outlook.com. Incoming emails are forwarded to your primary email which remains hidden from the sender. You can also reply to or send email using the alias email address.
Gmail also allows you to setup multiple email accounts which you can switch between when using webmail. Or just use an email client to easily manage multiple email accounts.
