Query regarding proof of concept

Hi All,

I have few existing reports and now I need to generate three reports to add some new functionality.

My query is

1.Do I need to build POC before developing reports ?

2.If yes,I heard that we must create POC on Excel only,Can we build POC on data source like UNX ?

3.Is POC strictly committed for static case or can we build POC on dynamic case ?

Thanks

Ram