Yes, those cheats are valid. Here is the cheats and their functions:
At the main menu, select "Options" then "Extras" and enter the following codes...
All Weapons: L,L,X,YY,R,R
All Missions: X,X,Y,Y,R,R,L
All Vehicles: X,X,Y,Y,L,R,L
Invincibility (In Take A Ride Mode): X,Y,L,R,L,R,R
After you have entered any or all of these codes, you can turn them on or off by going to "Options" once again from the main menu, and then "Cheats".
Select your desired cheat and specify "On" or "Off"
Enjoy these cheats and playing Driver 3!