The traits are the same as the already existing ones, but with a higher value.
The skills you can find out yourself. Every skill is available in a I, II and III version. (This includes skills that only start at Lt.Commander Level Attack Pattern Omega II or Attack Pattern Omega III are both Commander level BOs skills!)
Some III versions can be trained if you are the right class and have a Captain skill trained to 9 ranks.
Those that cannot be trained are only available via Rare or Very Rare Bridge Officers.
Examples of such skills:
Beam Target Subsystem 3 (all subsystems, but shields is particularly sought after)
Auxillary to Structural Integrity Field 3
Transfer Shield Strength 3
Reverse Shield Polarity 3