A few more things:

To speed up the process of cleaning the house, give the little people energy drinks. Warning: after 55, the energy drink will not speed them up.

You can usually tell what kids will grow up to be by watching what they like to play. Playing cook = kitchen career, playing office = office career, playing in the workshop = workshop career. This can be shaped by praising and scolding, like almost everything else.

If you praise a person a few times for doing a specific action, they will gain a "like" for something related to that. For instance, I praised one of my kids for "enjoying sounds of nature," the next thing I knew she liked crickets and birds. Go figure.

The more house upgrades, the happier your peeps tend to be.

The cooking class chance event will indeed give you a meal, but it will use lots of your food. And no, it doesn't make a big mess, usually.

Sometimes (oddly), the cleaners and maids will miss a few socks or wrappers. This happened to me a few times.

The garbage can maxes out at 20. After your peeps start walking with the black bag, you can just pick them up and the trash will automatically empty.

Only get the doctor checkup if your peeps' health is below 50%. Be careful though... I had 3 peeps in 1 family "weak" "extremely weak" and "a bit weak" and none of them had anything wrong, they were just hungry. I wasted $525. Oops.

If one of your kids walks really slowly, there's probably not anything wrong, they just don't like running. Cure this with the desensitization kit; ditto for any other bad dislikes, like a dislike of work (not kidding.. one of my marriage proposals disliked work. he was rejected. :P)

Finally... I have a theory about the 4 plates. They are serving plates, and the food is either finger food or the peeps walk around with forks and just pick the stuff up off the serving plates XD. In all honesty I don't really know :P