All three set ride height on a threaded body. What changes is how much of the damping you can adjust yourself.
Past V3 the dampers get more adjustment, or electronics. HLS lifts the nose for ramps, and H.A.S. lowers the car on its own dampers.
All three lower the car on a threaded body, so ride height is adjustable on every one. The difference is the damping. V1's is fixed: KW sets it for the car and there is nothing to adjust. V2 adds rebound adjustment, so you can soften the ride for the commute or firm it up for a back road. V3 adjusts rebound and compression separately, which is what lets you tune a car for the track without making it harsh on the street. If you will never touch a dial, V1. If you might, V2. If you go to the track, V3.
KW's V1, V2 and V3 kits carry KW's limited lifetime warranty with unlimited mileage. Each damper is dyno tested in Fichtenberg before it ships. The product page for each kit carries its exact terms.
A KW kit bolts in place of the factory struts and springs, but it is a suspension job: plan on a lift or stands, spring work and a wheel alignment afterwards. Most owners have a shop fit it. Cars with electronic dampers (EDC on BMW, for example) need the kit made for that option, and the title of each kit says which.
Every V1, V2 and V3 kit has ride height you set on the threaded body, within a range KW gives for each car. That range is on each kit's product page, as part of its fitment. Pick your vehicle above to see only the kits for your car.