No, acceleration is change in velocity. (And velocity is speed in a certain direction.)
If an object slows down, then it is changing velocity and thus accelerating. (In this case, the acceleration is negative.)
If an object changes direction, then it's velocity changes, so this is also acceleration. (This is centripetal acceleration.)
Nope. A force is an influence tending to change the motion of an object or produce motion in a stationary object. In other words, force changes velocity.
The legal method to change the KPH to MPH in a Renault Laguna would be to remove the speedometer instrument cluster and take it or ship it to an speedometer and instrument cluster service center where they can legally alter the MPH and KPH with all of the proper paperwork and documentation. Hope this helps!