Don't know much about the 3.3 engine. Believe 18 was first year for them. Never liked 1st year run of something however. The 6r80 trans is good enough. Most problems with them were programming or lead frame issues.
I didn't sound like they left the child. Believe both suffered burns and smoke inhalation. The delivery driver attempted entry a couple time too, but was quickly overcome by smoke and heat
Got stuck in that on way back from a run to Anderson Chevy to pick up a part. From the scene if figured the occupant was deceased. There was also a lady with a baby in the car tried to pass that scene on the shoulder and crashed as well. She's been arrested
I haven't had any issues coming up or maintaining temp at all. As far as higher temps, I pretty much am running at 225 or 250 exclusively so no input there