Hi Nalini,
My answers to your queries:
1. You can check if this sap-ui-core-dbg.js is physically present in your server location. Once you deploy SAP UI5 sca it should get copied to the following location:
C:\usr\sap\<SID>\<J_instance#>\j2ee\cluster\apps\sap.com\ui~five\servlet_jsp\sapui5\root\resources\sap-ui-core-dbg.js
The SAP UI5 version you currently have is quite old, you can try upgrading that also and then re-try.
2. The SAP UI5 library has js caching implementation which should ideally take care of changes in js files.
Best Regards,
Ria