could you please advise on the following?

Currently we have IP6000 configured to use ipv4. soon we'll get new devices which require ipv6. Will our old devices (which never going to support ipv6) be able to work using ipv4 at the same time, that is, will ip4 and ip6 devices be working simultaneously?

The server is used in private network (for Lab purposes, ip:10.x.x.x and 192.x.x.x) also running a DHCP.

Also when configuring ipv6, which method is preferrable: 1) configure eth0 and eth1 manually or 2) use 6to4?