Using who or whom

Here is the simplest explanation to get who or whom at the right position in a sentence.
Who is the SUBJECT -She
Whom is the OBJECT- Her

E.g: 'Who' told you about the news?
        For 'whom' you are cooking?
        'Whom' should I call to officiate the event? (Here, I is the subject)
       
Quick way to remember is through a song
Who took my heart away..~~
Add another following sentence
My heart is taken by whom?

This might sound peculiar but the correct English for 'who is she?' is 'whom is she?'.. T.T