Is it possible to customize kibana 4 for using it according to my need ??
That depends on the nature of your needs.
How can we do that ?? i mean if i want to customize kibana 4 where should i make changes?
Can i embed kibana 4 graphs or functionalities into another web app?
How can we do that ?? i mean if i want to customize kibana 4 where should i make changes?
You can of course make changes to the source code and rebuild. Depending on the kind of customizations you want to make there might be shortcuts.
Can i embed kibana 4 graphs or functionalities into another web app?
See Dashboard and visualizations | Kibana Guide [8.11] | Elastic.