You're right, Jason416. Parts purchases can be recorded as an expense.
Although, I'd suggest conferring with your accountant on the best way to categorize it.
Regarding the billing hours, you can either create a bill, expense or check, and add the hours worked in the Description/Memo field. Then, you'll have to manually enter the amount.
I'll include a screenshot for better guidance.
When you pull up the Transaction List by Vendor report, the information will show (refer to my screenshot).
Feel free to visit the Community if you have other concerns. We're just around to help you.