Mexicans dine late, so best bets are with an early dinner. The Hikers generally try to stay away from restaurants on Revolution. Unlike in the U.S., people selling music, flowers, or photos may interrupt your meal. Mariachi bands are ubiquitous, and while very festive, can easily overpower conversation. Mexican tap water is not potable.
Most restaurants serve bottled water.
If you feel unsure, ask for bottled or mineral water. We regularly order fresh salads and drinks with ice cubes and have not had a problem with Montezuma's Revenge - except in that teeny tiny dive way out of town by the dam. Walking in Tijuana is as safe as walking in any American city. You must be alert and watch where you are going. The sidewalks are full of cracks, the curbs are non-standard height and it is not uncommon to find deep holes in the middle of the sidewalk totally unmarked.