Multiple CELS what one do I need and change first

Sorry for a new thread I looked for a while and I didn't find what I needed and I need to figure this out soon i have a 2006 Acura RSX base model I just bought it a few months ago and the guy told me there's K Pro in it 2002 - 2004 when I got the car it already had CEL s for primary O2 sensor and knock sensor I've heard that I have to buy a certain primary O2 sensor which I'm pretty sure is 02-2004 Denso part number 235-9005, QUESTION 1. is that the correct part number for the O2 sensor I need? QUESTION 2. do I have to buy it a certain knock sensor or can I just get the knock sensor that my car is calling for? QUESTION 3. if I can't buy the O2 sensor and the knock sensor at the same time to replace what one should I do first? QUESTION 4. Does the O2 sensor for knock sensor especially the O2 sensor because as to be a different one than my car called for because of the cape Pro do they have to be OEM Denso parts? I have been buying all Denso parts for the car or whatever the OEM is money is getting a little tight so I'm just wondering if I can buy something less expensive to at least get me through for a couple months until I can buy the actual OEM thanks for anybody's reply sorry for so many questions just want to make sure I do this right.

Multiple CELS what one do I need and change first