Let's address your questions one at a time.
How to make report using the IRF information?
Do you want to make a report that shows people responses to questions on your IRFs? One way to handle this would be to have your PAM process log the responses to a file or log them as a comment on the ticket.
How users plan their own activity tasks during Change?
I'm not sure I understand this question. Please elaborate.
Anyone tried to be ITIL Compliant and had the same questions?
ITIL is a framework and not a set of rules with which to be compliant. Questions are always raised in every ITSM implementation.
We don't want to use Classic Workflow anymore, and don't want to create customizations to make the problem analysis available
Are you saying you don't want to create your own PAM processes?