The beveled part of the inside ring always is installed 1st or towards the inside of the car, the straight 90 degree edge is installed facing the outside of the car.

5mm spacers are hub-centric; they just do not have a hub centric hub machined as part of the spacer. They rely on what's left of you existing hub after the spacer is installed.

Here is a picture of a 5mm spacer on a Volkswagen MK4; the pencil is pointed to the portion of the hub that your wheel is going to use as the centering hub for the wheel.