If you would have told me 3 weeks ago I'd be excited to see ADR win another title, there's no way I would have believed you, but that was pretty awesome. Glad I didn't read the spoilers. I thought Ziggler was going to cash in.
ADR's face turn is changing that for a lot of people I find. It's really becoming easy to cheer for him.
I had a theory some time ago that people wanted to cheer him, but he was booked as a heel, and since his heel character was stale and wasn't booked all that well(in terms of drawing heat), they didn't have much of a reason to hate him, leading to no reactions.
Smackdown definitely pipes in music/sound. It's not genuine. I would be careful with those reactions.
They can, but they can't replace the actual crowd. Look at the crowd jumping up and down in the background at his win. Spoiler reports also said the crowd was hot for Del Rio all night. The reaction to his win was genuine.
The only legit reactions on Smackdown, in the past and now, from what I can tell, has been anytime Orton appears and The Rock's return tonight.