leak down test test for air leaks that can cause lean air fuel ratios and potentially burn a motor down, would have to be a big leak to do that but none the less you want to try to eliminate as much leaking as possible.
Complete rebuild by Fox then used maybe 25 passes on my drag bike. Bike has sat the last 3yrs. They are banshee shocks so they are 14.5" eye to eye. About as close to new as you can get for used shocks. Will come with air pump.
$500 shipped