missiles can be changed with ctrl and can be bought at the bottom left hand corner of the shop.
the 3 million gold asteroid worked with me 2/2 times however, the second time, i killed the asteroid and a neighbouring ship that died dropped it instead. perhaps you could try to kill the other ships while youve stopped time?
 "Enigmata"){kind=icon}
 "Dream World"){kind=icon}
 "Frontline Defense Beta 2"){kind=icon}
 "Adventure Ho!"){kind=icon}
 "Bubble Tanks 2"){kind=icon}
 "Feel the Beat (F2Jam)"){kind=icon}
 "Platform Racing 2"){kind=icon}
 "Stickman Madness 3: Stronghold"){kind=icon}
 "Typing Ninja Hunter"){kind=icon}
 "AstroFlyer"){kind=icon}