Take light layers of clothing that you can take off/put back on. This time of year on the waterfront, strong and cold winds come up while there is a bright sun shining. Nothing is worse than being miserably cold on a bright, shiny day, let alone a cloudy, windy one.
As far as fish tacos, Gayla's advice was right on. You can easily park in the multilevel pay and guarded garage that is slightly south of the fish market on the ocean side, next to a strip mall with a big Telcel sign and a Sanbourns coffee shop.
Take a tour through the extensive fish market and peruse the many accompanying open-air food vendors that offer tacos, seafood cocktails and many other tasty items, and eat at the venue that is most attractive. (Clue: If it is busy with locals = good place.) Otherwise, just evaluate the menu and the overall cleanliness.