A:
depends on where you live.
There are states (VA being one) where they are illegal....they DO have things that can detect this in your car - if you are going through a state where its illegal (and i advice you to check) put the radar detector IN YOUR TRUNK. Even if its in your back seat, they can still write you a hefty fine....but if its in your trunk, they cannot and dont let them bully you to convince you they can...
check your state laws, usually where they are illegal they will have something that can detect if you have it in your car....sure cops hate it, but where its not illegal dont worry about it