What if there are 2 parents and 2 kids (say age 12 and age 18 for example).

Sounds like most of the time you are going to have one person living in a two bedroom with  sometimes visiting kids.

Any recommendations about kids schooling is great also. 

UNLESS: The cost to remove all the pastor and install sheet-rock is low enough to justify the job.I plan on doing a lot of the work myself/ hiring friends or highschool/college kids to help.

For example, during the summer vacation, majority of the home owners buy and sell to allow their kids to transition to different schools.  

First letters of my kids and wife's name, AIS Properties LLC.

Here are the two issues, you're in the SoCal market so all logic goes out the window...just kidding, but still true.

Also, "family growing" can absolutely mean that your kids are getting bigger.  

What if tenants kids fall while climbing trees?

In GENERAL, typical SFH:Best time to buy (for lowest prices) is when kids are in school.