Representational? I strongly feel that no, art does not have to represent anything to be considered art. In the case of extreme minimalism I might think differently. A blank canvas does nothing for me unless it is a part of a greater collective with something profound to say. Otherwise, I just think the artist is lazy, but maybe that's just me, the layman.
What is art? Like the other two questions, art is subjective. It is whatever the individual person thinks art is. To some, Dog's Playing Poker is art.>
And I'm not saying it isn't! I really don't think any limitations should be placed on art and what is considered art, because like I said, it's all subjective and really our opinions stem from our own personal worldview...do they not?