A 4cyl performance engine is going to sound a lot different to a 6cyl designed to be Lexus smooth & quiet. You realise all ##GE engines have a head desiged by Yamaha? Does the car have a standard exhaust? Could it have a sports exhaust fitted? The RS factory muffler has a flap instide that opens at a certain rev range to aid in flow.
Your issue with the squeaky clutch is a common one, throw some graphite powered around the clutch fork & it may help. The other noise is the release bearing. Expensive to replace if you have to pay labour, most just put up with it until they replace the clutch.
As for lubrication;
Factory fill is 5.1L of 10W-30 or 5W-30. Being a performace engine you want an oil meating A3, B3, B4 or C3 spec, stay away from fuel efficent specs like A1, A5, C1 etc. If you're engine is high mileage (over 170K km) the you may want to look at a 5W-40 or 0W-40. Stay away from cheap semi syn 10W-40, the VVTi system doesn't like it. Service interval is 10K km.
Gear box takes 2L of 75W-90 GL4 (Motul Gear300 is the best option, Motylgear 75W-90 & Redline MT-90 are good/cheaper alternatives as well) Service interval 40K km
Diff takes 1L of 75W-90 GL5, if you have the factory torsen LSD then they like 75W-140 (helps them hook up quicker) Service interval 40K km or less if mineral oil used
Oil filter 90915-10003 / WIX 51394
Air filter 17801-46080 / WIX 46465