You can only shoot the yellow asteroids - 4 shots destroys them, less hits makes a hit noise and doesn't do anything else.
If the controls 'freeze', then you are either out of time (or destroyed)...are the large red time numbers at the top saying "00 00 00" (hours minutes seconds)?
I thought this would be a cool thing to do - have the game go on without the ship instead of just freezing
Red arrows slow you down too, so avoid those!
Collect the missiles (secondary weapon), and the I, II, III shot icons to give your self a primary weapon (or switch primary weapon).
Quick tap on the space bar fires primary weapon (if any).
Hold down space bar and release after 1 second fires secondary weapon (if any).