Absolutely. Shrapnel and unexploded AA ordinance were big concerns during air raids. Since you mention it, during the Pearl Harbor attack, a car of four(?) people on their way to work was struck by an AA shell fired from the harbor across the island, killing the occupants. I believe this photo is of the incident, but it isn't from the same angle as the one I remember so I could be wrong.

Most explosive AA shells came equipped with fail-safe detonators to set the shell off after a certain amount of time had passed and the round had therefore missed the target.

Once more, absolutely. The photo that MeneMeneTekelUpharsi linked to was widely published after Pearl Harbor and was used as anti-Japanese propaganda. Claims were made that the photo was taken of a car that was strafed by Japanese Zeros, but it was later discovered that AA shells were the suspected cause of death.

Civilian casualties due to stray rounds were also observed in aerial dogfights, especially in instances in which dogfights occured over highly populated cities. Civilians during the early months of the Battle of Britain would stand outside their homes and watch dogfights, but soon learned that stray rounds could injure and even kill them.

On a related note, civilian casualties due to stray bombs were also reported. One particular instance which I recall reading about was in Ambrose's Flyboys when a ball turret gunner in a B-24 allegedly watched a load of "dumped bombs" (armed bombs that were not dropped on a target, for whatever reason, which must be dropped before attempting a landing) fall directly onto a civilian farmhouse.

Absolutely. This was particularly common during the Battle of Britain, and there's some famous examples from the Battle of Los Angeles, too.

Check out this answer from one year ago, or this one from five months ago.