Some Cheats:
Press Ctrl-W, when you hear the low double beep tone type in battlecheat to enable in flight cheats.

Then Type:
canttouchthis - Invincibility
fillerup - Unlimited Flight Range
Various Cheats

Press Alt+E at main screen and press the following:

10 000 000 credits: PAYDAY
All research: KNOWITALL
Build Base fast: QUICKBASE
No Aliens: JOYRIDE

Side Missions:
Arms Dealer: SMARMS
Recon: SMRECON
Nova Bomb rescue: SMNOVA
Pirate Rescue: SMRESCUE
Pirate Freighter: SMROUGE