Don't start with the l33t stuff
in mission 2 if you saved the last 2 Transports you get elite pilots, which spews out Elite Ships from Bannana-2. First is 2 squad of Elite Bombers (And BOY are they elite). The 2nd is squads of Pulsar Corvettes (IIRC).
How do you get them normally? or are they just "Special SP units"? Because I see no indication of Ships gaining exp in HW2.