G'day Falchoon. To answer the questions in chronological order :
1) It won't affect the computer
2) Yes it will bring gains, but they will be fairly minor, and possibly not noticeable in the "seat of pants" measurement system. Technically, a better filter will give better airflow, which of course is a good thing!

I doubt there would be any noticeable gains in economy either, but on paper quite possibly!
3) K&N make great gear for reasonable prices. For panel filters, I tend to think they are the pick of the crop.
As far as pod filters are concerned, these are great but need some work to fit and aren't much use unless you really need one. ie. you find that with all your intake mods, the panel filter just doesn't give enough flow. A good compromise is to have a "cold air" intake setup, but still using the airbox and panel filter. Check out the tech pages on our club site :
http://www.nswxrclub.org.au/techlibrary/coldair/coldair.htm
Hope this helps mate! :thumbup: