Hi,
We are creating Opportunties and mapping them to "Contact" / "Company" and "Campaign" (for us Campaign is Event)
We have few Stages while creating any Opportunity i.e. Initial assessment, Needs Analysis, Proposal sent, Contract Received and Declined.

We would like to see the performance of any Campaign, companies w.r.t. opportunities created under them.
This is the very basic Salesforce vanilla functionality we are using, but having few issues:
I had attached all possible screenshots which will highlight the issue more in detail:

What we want is:
AT Event Level:
# Field "Num Total Opportunities": Count of all Opportunities created under this event
# Field "Total Value Opportunities": Sum of all Opportunities Amount created under this event 

# Field "Num of Won Opportunities": Count of all Opportunities created under this event having "Stage" = "Contract Received"
# Field "Total Value Won Opportunities": Sum of all Opportunities Amount created under this event having "Stage" = "Contract Received"

Question 1: Are the fields given by Salesforce (Num Total Opportunities, Num of Won Opportunities etc.) can be edited/formula can be put ?
Question 2: If NOT, can these fields be hidden? SO that I will create 4 custom fields to solve the requirement.
Question 3: I had created a custom formula field under Campaign and tried to put the formula, but unable to fetch "Opportunity Stage" and unable to fetch the SUM formula.

I will highly appreciate if a kind soul can help me as the Vendor dealing with us is unable to help here.

Thanks,
Siddharth
CRM Manager