Porting and polishing the supercharger will lower your outlet temps thereby reducing any KR and possibly allowing you to drop pulley sizes without increasing KR. I believe some members were able to drop .2" after some P&P work. As always, whenever modding be sure you SCAN your car for KR to make sure you're not getting any. By the way, your supercharger inlet is the point of greatest heat gain and will benefit the most from the P&P.
Please do your research before you risk butchering your supercharger though. It'* also a good idea to replace your needle bearings afterwards too.
Do you have a press available? You'll need them to seat the bearings.
Only if you change them. If they are good and you cover them with tape etc. Then it can be done w/o changing the bearings. I would suggest changing them while you are there, however it is possible to do it without.