Hi Sabarinathan,
You can implement the add-ons for the Fiori apps on the ECC 6.0 EhP5 that you currently have. But be sure not to use the old launchpage and use the new launchpad instead. Also since the OData integration components are the same for older EhPs and EhP7 (refer Group A/B and Group C in SAP Fiori - Add-on quick reference for transactional apps) there should not be any issue in the implemented apps after the EhP7 upgrade too.
Regards,
Saurabh