The disallowed goal was as a result of Sanchez flapping at the corner and gifting the ball to the West Ham player. If he had cleared it initially there would have been nothing for VAR to deal with.
We've had more than a fair share of luck this season, Liverpool's third goal at Anfield when Mane was deemed to have hand balled when Sanchez made a cluster **** of a clearance was another one.
Agree with you totally on the fouls, in terms of offside the clear and obvious error rule does not apply though, it is down to Hawkeye as the decision maker.