Can I make/receive phone calls with phone number attached to iPad's Verizon account?
It serves only to make Verizon's back end provisioning work. You can't call to it, you can't call from it, you now just know it's not a "real live telephone number". 

Pretty silly as there's a limited number of numbers that can exist in any one area code, but that's how things are engineered at present. Other carriers do the same thing, so it's not just vzw.