Calculation Periods and Duration from start and end dates

As the timeline in Project 2013 is restrictive when dealing with lots of Gantt lines (I have 64 initiatives in this portfolio), I would like to use the Visual Reporting to provide information that I can plug into the Excel Project Gantt Planner template. In that Excel Project Gantt planner, I need to calculate start dates and time in MSP into periods – which I am happy to do (if I knew how to do it). So I need to customise a column, using a formula to calculate.

1.
Plan Start Period Number
Assumption P1 is the first week in 2016
Formula: Look at base line date and assign the start period, e.g. 4/1/16 is P1

2.
Plan duration number of periods
Formula: Look at the baseline start date and baseline end date and calculate how many periods, e.g. statt4/1/16, finish 15/1/16 number of periods = 2

I will 2 other calculations e.g. Actual Start and Actual Duration, but I will be able to work those out form the formulas above.

Many thanks.