Hi Mayank,
Basically the Cost Plan should give you the details what you are after. When you create a CP from Task(populate from Task Assignment), the ETC of the resource of the role/resource assignment * rate in the matrix gives you the planned cost which is your forecast. The actuals (from timesheet or transaction entry) * rate will give you the actual cost.
You can use the Cost Type as grouping attribute in CP which will give you the cost based on Capex & Opex.
You can also use the ETC from the team to calculate the forecast cost and actual cost - populate from Investment team.
This is a very high level explanation of how to achieve what you are after, but if there is anything specific, please let us know.
Thanks,
Jerin