To get Master difficulty level, beat the game on Hard. After that, go to Option and set the difficulty to Master. Remember, this mode is extremely difficult.

To get "Free Play", simply beat the game on "Hard" once. Then go to "Option" mode and set your "Credit" option to "Free" to get unlimited continues.

At the stage select screen, hold either Triangle, Circle or Square on the player 2 controller. While holding this, select your stages with the Player 1 controller. This will give you one of three different ships (Depending on which button you held on the 2nd player controller). The ships' attack power, speed, C.R.A.W. recovery rate, and number of carry-able C.R.A.W.s will differ, but the only change in physical appearence will be the color of the ship.