For your first request:
Just read the manual or press f1 in the game.
Second:
But.. why? If you never played the game before (sounds like it) there'd
be no challenge if you just turned on cheats and roared your way through
the 6 levels with unlimited ammo and invisibility. Trust me when I say
Hi,
No offense, but if this is your first time playing you will sorely be
disappointed in the game if you enable the cheat codes. Reason being
is certain cheats such as the invisibility cheat make it impossible
for the enemy tanks, bases, etc to fire on you. I recommend playing
the game a while