What is the process flow in MRP - MD61+MD01,MD02+MD04+COR7

Hi experts,

I need one clarification for Material requirment planning ( MRP - Process industries )

My company is newly implemented in SAP so i want some clarification in MRP side.  My company flow is 3 rd level converted of FG.

1 st level - Raw paint - Samifinished

2 nd level - Tin condition - Samifinished

3 rd level - Case condition - FG

I have raised PIR in MD61 at FG code, after MRP Run planded order created at three level ( 1 st, 2nd, 3rd - level)

But what is the t.code used is correct recording MRP Run - MD01( Plant level ) OR MD02 ( Single item)

what is the t.code used for over all requirment Bill of material list ( ROH & VERP)at plant based recording purchase the material.

Kindly pls explain the flow for PIR > MRP RUN>STOCK RECUIRMENT LIST> PLANNED ORDER TO PROCESS ORDER>

Thanks,

Umapathy