Two reasons for using Flows instead of Apex code are:
Flows can be modified and created without a developer. Flows are declarative tools that allow administrators to build complex business logic using clicks instead of code. Flows do not require any programming skills or knowledge, and they can be easily modified and maintained by administrators.
Flows provide a visual debug process. Flows have a built-in debugger that allows administrators to test and troubleshoot their flows in a graphical interface. The debugger shows the flow execution path, the values of variables and sObject fields, and any errors or warnings that occur in the flow.
Verified Reference: https://help.salesforce.com/s/articleView?id=sf.flow_builder.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.flow_builder_debug.htm&type=5

The best way for the administrator to recommend tracking the kits so that they remain grouped together during returns in Order Management is to use custom attributes. Custom attributes are fields that can be added to objects to store additional information that is not available in standard fields. The administrator can create custom attributes for the Order Item Summary object to indicate whether an item is part of a kit, and what are the other items in the kit. This way, the kits can be easily identified and handled during returns. Verified Reference:https://documentation.b2c.commercecloud.salesforce.com/DOC2/topic/com.demandware.dochelp/OrderManagement/Administration/AdminAttrMgrCustomAttributes.html

The best way for a user to view the information exchanged between the payment platform and the external payment gateways is to navigate to Payment Gateway Logs related list on the corresponding Order Payment Summary. A Payment Gateway Log is a record that captures the request and response messages between the payment platform and the external payment gateways, such as Stripe, PayPal, etc. A PaymentGateway Log has a lookup relationship to the Order Payment Summary object, which represents a payment made for an order or part of an order. A user can use the Payment Gateway Logs related list on the Order Payment Summary page to view the details of thepayment transactions, such as the request and response payloads, status codes, timestamps, etc. Verified Reference: https://help.salesforce.com/s/articleView?id=sf.order_management_payment_gateway_log.htm&type=5https://help.salesforce.com/s/articleView?id=sf.order_management_order_payment_summary.htm&type=5