I can size the columns and beams for Gravity loading only. You will need to be sure there is adequate lateral resistance and the footings are adequately sized and that the connections are properly engineered and detailed. What spacing do you want for the beams?
You will need to ensure the deck can span the 12' between the beams. Cantilevered columns are not a good lateral system in a seismic zone.
You can plan for W8x18 beams ASTM A992 Gr. 50 beams with 3" nominal poor columns. The connections will need to be detailed to brace both the beams and columns. This assumes a maximum deck dead load of 30 psf and live load of 40 psf.