Traffic on Mondays is usually the best of all weekdays to travel. Traffic on Friday mornings is also light, but gets heavy as the day goes on. Yes, you can walk through the old zoo. The cages use to be open, but they're now locked. It's kind of creepy cool. Yes, you can take pictures.
I do remember something on the news about Godzilla getting a star. I think it was several years ago. However, the stars to me are no big deal. They're stars with names on them. It's cool to look at the stars as you're walking along the streets. But I know people that come out here to look for a particular stars name and when they get there, it's a let down feeling. So, maybe don't put too much into it and it would probably be cool to act like you stumbled upon it for your boys.
I was also a big fan of Emergency. It's located in an industrial area right off of the 405 freeway. Of course, it's in an older area, but you'll be fine.
Smart thinking of not driving down to DL at 4:00 p.m. I don't think traffic will be that bad. You'll be going against the main flow. Traffic should lighten up by 6:00 and even more by 7:00.
A tip: If you drive in the far left lane out here, make sure you keep up with the car in front of you. If not, you're going to get run over and hopefully nothing worse.