Organizing a car for a year (Seattle)

Hi,

we are relocating from germany to the Seattle area. We plan to stay 12 months.
Amongst all the things we need to organize, I will need to find a car.
So far, my best idea is to buy a used car cash (as I don't have a credit history etc.) and sell it after one year.

Are there any do's and dont's here? I am especially looking for tips re/ insurance for foreigners and dealers that might even be willing to buy the car back.

Many thanks for your comments!
Helge