I am the administrator for my brother's estate. This will be an insolvent estate. He has a vehicle that ~$8500 is owed to the lender. I would like to purchase this vehicle for myself. How do I do this so that it will not become property of the estate when it is paid for? Thanks!

You determine the blue book value of the car. You then pay the estate the value and have the estate issue you a bill of sale.

Do I write a personal check to the checking account of the estate and then pay the vehicle off with a check from the estate account?

That's the way I would do it.