1.Is there any third-party (free) tools available for migrating crystal reports to SSRS?
2. is there any detailed step by step document for migrating Crystal reports to SSRS?
3. BEfore migrating we have to set any SSRS configurations in existing SQL SERVER?
not in my knowledge. the one from MSDN you are reffering is one of the good document. Microsoft had so online webcast on this too but its long back, you might get that video downloadable from somewhere.
In your given link download link is not available that is trial version.