CL-BOB

recent owner of 01 cl type-s , just have few questions so i can take care of the car

1. is there any way to tell if the transmision has ever been replaced?

2. how does this jet mod look like thats suposed to add extra cooling to second gear?

3.i bought new sparkplugs but i dont know if i should change them , has anyone had any bad oem sparkplugs ? im @ 60000miles almost , and bought the ngk iridium plugs,

4.i also bought 1 bosch o2 sensor and im thinking replacing the one closer to the engine , should i ?

5. i also want to change the transmission fluid but i hear that might actually couse the transmission to fail sooner ... is there any truth in it ?

6. i read somewhere that the cl auto trans has a performace shifting ....would that be reffering to the sequential shifting or is the a performance mode for full auto ?...im asking because i wouldnt want to have this turned on all the time and not knowing about it ,

thank you for your great support , bob