We are local and my DD lives in Orange so we don't have to pay for a hotel. But if we did you can get great prices for places that are not that far away (like 15 minutes away).
#3. We buy a SoCal pass. The one with the block out dates on the weekends & during the summer. Wouldn't want to go then anyway. I go to the park at least twice a month, more in the fall. I Also buy the parking pass.
#6. Pack our own necessities.
We load up on snacks and bottled water and put it in a backpack
#9. Don't buy bottled water.
And one that wasn't mentioned. We bring an ice chest filled with stuff to make sandwiches, we also buy chips, cookies and other munchies. We go out to the car to eat and get off our feet for an hour or so during the hotest part of the day. It's actually very cool in the parking structure after all the cars have sat idle for awhile AND when we go to eat we can usually find a parking space near the escalators so we move. Just make sure you get to the park early enough to park in the structure.