Factoring other Expenses for each Job?

I am confused by your question as you are mixing direct costs [employee labor] and overhead [Insurance, vehicle expenses]. Could you please clarify.

Will

I want to take the total direct costs and the total overhead costs and factor that amount into the estimated costs of a job to make sure that we are estimating high enough to cover all direct/overhead expenses.

OK, create "double-sided" Items for your Job Costs, allocate the Cost side to a COGS type account and the Sales side to an Income type account. Then use these Items in all your Purchases from Vendors and in your Sales [Invoices} to Customer/Jobs. Make sure your choose a Customer/Job for each transaction. Create both Payroll and Service Items for your Employees and Service Items for your subcontractors.
For Overhead- use Expense Accounts and the Expense Tab. The Profit/Loss Reports will then show both the direct costs-COGS and the Overhead- Expenses. Once you have this information then you can decide how to determine/apply Markup. Whole books and numerous websites/blogs have been written on this subject and there are several different ways to add the Markup in QB.

Will