Bonus level:
Enter "WAKYLEVL" at the ID selection screen.

Cadillac:
Enter "NEWWEELS" at the ID selection screen.

Invincibility:
Enter "CLEVALAD" at the ID selection screen.

All primary weapons full:
Enter "GUNCRAZY" at the ID selection screen.

All secondary weapons full:
Enter "MAXMEOUT" at the ID selection screen.

All time pick-ups ten minute:
Enter "WAITABIT" at the ID selection screen.