"What do you like?"
Lubisz is you singular and lubicie is plural. Just like ty is singular and wy is plural.
Did it not accept "co lubisz?" both are correct.
As you know English does not distinguish between ty and wy- both are you.
Sounds very strong like "What do YOU like?" - I think it's a bit too strange to accept. If only there was some "and" at the beginning of the sentence, then it would make a lot of sense: "A co podoba się WAM?"
No. That would be more or less equivalent to "Do you what you like", or something like that.