Which will work until they roll it out fully and someone counters it with some new ad blocking. Might be more complicated than current options, but it'll be there.
Oh, for sure, or maybe some statistical method that doesn't require that much processing. I don't doubt it'll work, though. Google is wasting their time and energy with this.
Easy, just do it like old school MythTV commercial detection. Buffering will be annoying, though, as you'd need to load the video far enough in advance to skip.
Doesn't really matter. Ads are blockable by nature as they will always contrast with the content and are always the same. Worst case we might get a black screen for as long as the ad goes, but we'll always be able to block them. There's nothing YouTube can do.