Consulting on PWC price setting

Hello, I am a little confused about the price setting of ProcessWaterCenter (PWC), may I ask you about them? PWC and related units are shown in the figure below. Thanks for your help. Wish you a good day.

a) I have set the price of the process water by ```PWC.process_water_price = 0.0008```, but when I call the price of stream ```3-PWC```, i.e. ```Makeup_process_water. price```, the price of Makeup_process_water stream is still 0. But the Process water in excel Utilities has a price of 0.008 (as shown in the following picture)? So if use ```PWC.process_water_price = 0.0008```, will the cost of process water needed to be supplemented be taken into account in the calculation of TEA?

b) When I change the price of the Water_need stream (```Water_need.price=0.0005``` or ```Water_need.price=0.0009```), the minimum price of the product will also change, but theoretically, the cost of the process water required for the process should be obtained by multiplying the price of the supplementary process water (```Makeup_process_water.price```) by the flow of the supplementary process water ((```Makeup_process_water.F_mass```)). So the change of Water_need stream price should not affect the minimum selling price of the product?

c) Should the price of ```Water_need stream``` be set to 0? That is, should only the price of ```3-PWC stream``` (i.e. ```Makeup_process_water.price =0.0008```) be set, and the price of the remaining water-related stream (including ```Water_need, PWC-0, PWC-1```) be set to 0, right?

d) If WWTP gets more RO grade water than makeup water of boiler, do I still need to set the price of boiler makeup water (i.e. ```Makeup_water(RO_grade)``` stream of boiler)? Do I still need to set the price of ```Makeup_ RO_ water stream``` of PWC? If still need, is it set by ```a=1-PWC, a.price=0.001``` or ```PWC.reverse_osmosis_water_price=0.001```?

e) If I want to set the price of the process water that needs to be supplemented for the process, should I use ```a=3-PWC, a.price=0.008``` or ```PWC.process_water_price=0.008```?

f) The ```Cash flow``` data table in Excel seems to be wrong. The operating cost is not the cost of net consumed materials, but the cost of initial input. Could I consult you what code can be used to obtain detailed cash flow analysis results, including ```FCI, VOC, material cost, utility cost```, etc.