Re “
Does the aircraft need to be able to stop on the MED setting if it is to be allowed into a particular runway?” (#8)
All aircraft must be able to stop within a % the total runway length available depending on the conditons (60% for a dry runway). There is no mechanism for the autobrake, at any setting, to guarantee any particular stopping distance.
Auto brake can only demand a particular, selectable deceleration by modulating the brake pressure and then it is limited by the anti skid system.
The stopping distance depends on the runway conditions, the runway friction, and whether any additional deceleration device is available, e.g reverse thrust, spoilers, or airbrake. Where the runway friction is very low, then even with max brake pressure, the selected deceleration may not be achieved. In these conditions the aircraft may not be able to stop safely, i.e. contaminated/slippery runway operations not allowed at LCY.
Ref:
Landing on Slippery Runways - Slides 16-17