From what I've seen from a Toyota tech the CEL may not be able to be cleared with a code reader. It might only be cleared by key events, which means now that you have gone back to stock the computer will only turn off the CEL after a certain number of cold starts, he said up to 50 for Toyota...
All HVAC systems use the AC to dehumidify the air. It cycles the AC on and off all the time. On the old systems you could actually turn off the AC and you would see people in the morning driving down the road wiping the water off the inside of there windows.
I just did my first engine oil change at 469 miles. Yes I'm one of those guys that does the first one early to get out all of the crap out so the filter doesn't plug and get bypassed. And as usual the oil was as black as an old diesel when it came out, I haven't opened the filter yet but it...