Advice needed-What insurance do i need for US rental

[sevenstar]

Hi,
basically what insurance do you need when renting in the US so that if something unexpected happens that you dont lose the shirt off your back?

Can you insure your liablity for the plane you are renting and also third party damage or injury(ie people/propert on the ground)

If so who does it,where can i get it from and how much does it cost?

Also if you fly with an instructor in the US with a school or or FBO are you covered by them as your technically not pilot in command?

Thanks - this is wrecking my head at the moment