Pro mode for wheels is only for non-DFP-G25 wheels.
Noob mode is actualy called "Normal" mode, since it is GT4's arcade mode physics more-less.
It is located on pre-race menu, and it is "shorter-text" of the second option. Longer text means professional.
As for S-4, here is the walktrough - and it can only be done on "Normal/Noob" mode. Drive behind the SL55, brake early and try to overpass it from inside (watch the blue wall) on turn 1. Do not hurry to overpass TVR, you have time.
Let the TVR do its mayhem on the first 180 turn. Keep the outer side of turn to avoid any collisions and keep your speed. When exiting, you should be somewhere behind R8 and/or Lexus because other cars are taking inner-side of turn and they all brake heavily. You have enogh power to keep up with them, but be aware of the incoming middle-180 turn. Keep the inner side this time and try to get in front of Lexus when exiting. You can easily overpass the M3 before exiting to oval, or just after getting to oval.
Use the draft to catch R8/other car, and you should be around 7/8 seconds behind leading gruop just before entering the oval-chicane. The chicane is crucial, you have to have fast-in/fast-out, and mantaining the balance is crucial. Your exit speed should catapult you to the rears of leading group, and then you need minimum skill to overtake them seconds before finish line.
Your main problem are penalties, so key is to aviod any contact. 599 power is more then enough for this event, so just master the process. I earned 100 million in hour and so by this event, so it's worth it