flashing the w610i firmware will change loads u will gain walkman 2 better sound, u will lose all ur k550i settings and any files, yes u can just flash back to the k550i again if u don't like it, xs++ and setool2 is computer software u run it on a windows pc, ur xs++ log will be where xs++.exe is on ur computer it will be called xs++log.txt, no no1 can provide u with the firmware u will have to find it urself. u might find this guide useful Tutorial: Flashing K550i to W610i - SE-NSE Forums