Will it be able to read,open, edit a pdf file which was created in Acrobat X Pro with Acrobat 9 Pro? any exception? any specific version for 9 Pro? or any 9 Pro version can do it?
It depends. Generally-speaking the content of PDF files created in Acrobat X will use PDF/1.7 as the base level so will open in Acrobat and Reader 9, but there are exceptions, including:
All PDFs created in Acrobat (Standard or Pro) will open in the same version of Reader, Standard or Pro - it's only the creation/editing features which vary between flavors.