A carrier in today's navy is a CVA(Carrier Vessel Attack). If it's a nuke, add an N.
CA is 'Cruiser Assault'.....i think.
5x5 means everything is good to go. I think this is mainly pilot jargon, but i've heard that said in the army a few times, and it always meant basicly "A OK"
I have no idea what the 5's represent, or the origon of the term, though i would be interested to know.