Does it automatically record over old footage when the hard drive is full ?
Yes it does. Just check ur setting
How do you install it?
You mount the cameras at where you want the field of view to cover the areas that you want. Then run the cables from the cameras to the receiver. Put the receiver at the place where you don’t want the thief to see so they don’t destroy it upon entering your property. Then plug in the power. Turn it on and follow the instruction to set up your remote view etc...