The expanding ship sounds original. However, your descriptions of ship upgrades seem to fit a verticle shooter best. Sounds like the player would start out with a boring looking pencil of a ship.
With powerups, wings would be attached and it would look like a pencil with wings.
Then it would acquire laser cannons and look like a pencil with wings, and laser cannons.
Then it would acquire a speed-up which would cause it to look like a pencil with wings, laser cannons, with smoke farting out the eraser for 10 seconds - do I get the picture?
"Power, precision, and don't forget about speed. If you practice everyday with these things in mind... you begin to develope A FIGHTING MODE." - Fist of Legend (Jet Li)