No - Cisco firewalls do NOT allow for a loopback address. If you are having issues with pinging a certain interface IP address, please be sure that you are pinging the interface closest to the client machine - ie NOT another interface. Unlike a router, the Cisco firewalls do NOT allow you to ping a "far-side" interface. Also, be sure that you have 'icmp permit ' for the relevant interface.
Not entirely true. You can issue the 'management-access inside' command, which will enable you to SSH and issue ping/snmp commands on the inside interface IP eg. from the far-end of a IPsec tunnel configured.
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...