NASA chose the flying-saucer shape for the LDSD because the Curiosity Rover descended to Mars in a module of the same shape. To test the device in Mars-like conditions, it has to experience an atmosphere that is 1% as dense as Earth's, and this can be found at the edge of Earth's atmosphere (which is why the prototype has to fly that high).
At this point, NASA is seeing if launch conditions will be good at the end of June.
Background on the LDSD:
Article on the delays:
And, the updated news that all launch opportunities were missed: