Project Expense Resource planning (Rate based and manual entry) questions

Summary:

Our customer had the below scenario

First Challenge- They want to plan their resources based on specific quantities for a limited number of resources, such as tablets (Rate based planning), and manual entry planning for a limited number of resources. Now, the question is how should we establish a revenue generation method: manual entry or rate-based? Which method would be suitable for meeting the aforementioned requirements? If we keep manual entry, revenue amount is not generated for Tablets.

Second Challenge- Regarding the customer's data, it seems that they have separate accounting periods for helpdesk costs and helpdesk billing. They do not have cost and billing in the same accounting period.