I like guys who are tall dark and handsome
does dark refer to someone's mysterious or someone who has dark colored skin?
Should ability be plural? I heard it's uncountable. Is that the same for skill?
His ability of playing the piano is fantastic
His abilities of playing the piano is fantastic
His skill of playing the piano is fantastic
His skills of playing the piano is fantastic
#2 There is no "should" about it - either can be used.
nb: His ability to play the piano... / His abilities at the piano...
His skill at playing the piano.../His skills on the piano....