all correct
correct
Это более дорогие часы, чем те
correct
Этот урок легче двадцать второго.
it is correct but it's not 100% clear
Because in Russian all nouns have gender, sometimes you need to specify which noun you meant
In this sentence both шапка and продавщица are nouns with feminine gender, because of that it is unclear what the parents didn't like - the cap or the saleswoman
English sentence suggests that the parents didn't like the cup, so to be specific you need to say something like this
Продавщица показала моим родителям чёрную меховую шапку, но шапка им не понравилась.