what (free)program should I use to edit and save the CRW file from CHDK for the SX10?
Since most applications do not work directly with the 12bit CHDK RAW files of the new cameras,
you should enable the CHDK DNG support (have a look to this
forum link: Enable DNG support guidance (SX10)), most apps can use the DNG RAW files...
CHDK DNG's contains the "true", RAW sensor data with additional header informations (EXIF meta data, whitebalance & color matrix informations...), it's lossless & standardized...
DNG file format @ wikipediaYou'll find some apps on the CHDK wikia
Software list, e.g. XNView as viewer, GIMP with the UFRaw plugin as powerful editor...