You don't have to format the card in the router. You can do that on your PC. Just format the CF-card as FAT32 and plug it into the ASA.
BUT: If you just want to "upgrade" the old card with a different one, then first attach the original card from the ASA to your PC and copy all files (including the hidden ones) to your PC and then copy them back to the new card. That way you also move your licenses to the new card which are stored in hidden files and your private data like keys.
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...