The rules are different for delays and downgrades, so 1 and 2 are not the same.

The compensation for delay is dependent on miles flown and the delay in hours. Class of booking is not relevant.... The max compensation is €600 per passenger. And the regular duty of care like hotels and meals.

The compensation for downgrades is more a case by case basis. And it's more the operating airline that determines what the fare difference is. Compensation will be monetary, rules are a bit unclear. But the compensation should not be in miles.

US DM normally doesn't care if one of your legs is downgraded....