Please do check to have service password-encryption enabled in your device.
As far as i know for snmp you are not giving any key.... you give only the string which will not get encrypted. If you have enabled the service password-encryption in your device. Then your tacacs key will get encrypted to level 7 encrption automatically. Else it will take 0 by default with plain text. But this also even it will not do md5 encryption for those password.
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...