Needing assistance with platform-migration

the masterkey [f5mku -K] is used to decrypt the encrypted 'stuff' [password in auth configs, health monitors [ldap, http basic, etc..], ssl key passhphrase] in your ucs. so if you are restoring a ucs from another device, its worthwhile have this available. grab the master key from the source device and 're-key' the master key on the destination device.

not so sure.. but I would say yes.. the ucs takes care of these keys and i think dnssec keys will be included.

reusing the self ips is fine, just dont enable the interfaces [vlan/actual traffic] until you are done with initial config setup. enable only the mgmt interface. premature enabling of interfaces - same vlan on your old and new bigip - can cause you an active active state.. even if they are not in HA.