Explanation
You use an invoicing plan in this scenario. An invoicing plan is a method of creating invoicesautomatically at predefined intervals or dates without referring to any service entry sheets or goods receipts. You can use an invoicing plan for blanket purchase orders or contracts that have a fixed amount and validity period.
References: [SAP S/4HANA Sourcing and Procurement | SAP Learning], Course S4520, Unit 2, Lesson 1.

Explanation
To enable automatic generation of the purchase order at the time of goods receipt without a corresponding purchase order, you must meet the following prerequisites:
Automatic purchase order generation is activated for the movement type in Customizing, which means that the system will create a purchase order automatically when you post a goods receipt with movement type 501 (Goods receipt without purchase order).
A default purchase order type is specified for the goods receipt, which determines the document category and number range for the purchase order.
A valid purchasing info record exists for the material and supplier combination, which contains information about the conditions and delivery data for a material from a specific vendor.
References: SAP S/4HANA Sourcing and Procurement | SAP Learning, Course S4510, Unit 2, Lesson
1.

Explanation
To determine a price from the info record, the system uses the following logic:
The system always proposes the valid plant-specific price, if available. This means that if there is an info record for the material and supplier combination at plant level, the system will use the price from that info record.
If there are no valid conditions, the system can propose the price from the last purchase order, if available. This means that if there is no info record or no valid price in the info record, the system will use the price from the most recent purchase order for the same material and supplier combination.
References: SAP S/4HANA Sourcing and Procurement | SAP Learning, Course S4520, Unit 3, Lesson
1.

Explanation
If you want to implement production planning and product costing in your company, you must choose plant as the organizational level for stock valuation. This means that each plant has its own valuation area and valuation class for each material. This allows you to valuate materials differently in different plants and calculate production costs accurately. References: SAP S/4HANA Sourcing and Procurement | SAP Learning, Course S4550, Unit 1, Lesson 1.