[tor-relays] More IPv6 questions

[Paul]

https://trac.torproject.org/projects/tor/wiki/TorRelayGuide#Parttwo:technicalsetup

uses "ORPort [IPv6-address]:9001"  - so can i use the same port number for IPv4 and IPv6?

If I run more than one instance on the same machine, can i use the same IPv6 address like in the first instance - as i can do in IPv4? 

"ip addr|grep inet6|grep global" doesn't give an answer on every server - what to do instead please to fill the square brackets?

Thanks Paul