The road test for us was never more then 4-5km usually, long enough to test cruise control, handling, brakes, and listen for road noise.
If it's a brand new car that won't be demo, it'll prolly be <20 km
Most likely less. Might depend on which factory it came from and if it was a single truck delivery.
I would go over it good, make sure there's nothing substandard in terms of cosmetic. Some leases don't include certain cosmetic repairs after lease. It's been 6 years or more since I've done a PDI on a lease so it may be different now.
If you can take it for a spin it wouldn't hurt. Make sure there's no weird noises.
Nice thing with leases is they may end up taking the vehicle back, and its generally under mechanical warranty for the duration of the lease so they rarely skimp on the inspection, as it'll just mean it's gonna be back for a repair that they have to handle.