Using IPv6 addresses with existing Infinity connection with 13 static IP addresses

I have had an Infinity connection for years now, using the HG612 VDSL modem and BT Business Hub 3 originally supplied by BT with 13 static public IP addresses and have been very happy with the service. 

If I was to replace the Hub 3 with something more recent that supports IPv6 (Hub 4 or 5, or a Draytek 2860 for example) I have some questions:

    1. would I still be able to use these IPv4 static public IP addresses?

    2. would I have to apply for static IPv6 addresses as well, or would they be automatically become available

        in a IPv6 /56 subnet?

   3. could I use both the existing static IPv4 addresses as well as the IPv6 addresses?

Thanks in advance for any ahswers to these questions.

Andy