To switch weapons use mouse wheel. Once you have the grenade laucher fire at the rock till a smaller rock pops out each one gives you 5 ore. You need 20 to get 100million credits as I hacked the refining in this game for now. Once you get 20 ore you have to goto the refinery which is located inside the base and has a tower sticking out of the top go inside and you will see a VENT like thing get near it and a prompt will appear. once refined you will get your money and then you can make vehicles in game. There is a vehicle factory which is inside a red building with a ramp. Fighters are located at the starport just jump into the elevator to get to the top. Once there there are consoles that create the fighters just explore a bit you can't miss them. To get it just walk around till it prompts you to press e to enter and the controls for fighters are the following
WASD <-- flight controls
Mouse 1 (left mouse button) fire weapon
Spacebar : lifts the vehicle upwards or lets the player hover if they tap spacebar.