1) How do you express "roll of rate"? Like speed can be km/h, roll of rate????
Roll rate is the rate of change of the angle of bank, ie it's a measure of how fast the angle of bank is changing. It is usually expressed in terms of 'degrees per second'.
But are you sure that each SS deflexion has an aileron/spoiler movement at each speed?
I can't speak for all Airbus types, but from the A330 FCOM:
'When the aircraft is on the ground (in “on ground” mode), the sidestick commands the aileron and roll spoiler surface deflection. The amount of control surface deflection that results from a given amount of sidestick deflection depends upon aircraft speed.'
2) In ground mode, when you take speed, the aileron/spoiler movement reduces with stick deflexion. True? So each side-stick deflexion at a given speed has a programmed aileron/spoilers movement. Right? So if you turn at 15kts or 25kts with same Side-stick deflexion, you will make a same turn because aileron/spoilers movement will reduce at 25kts.
The first part is right, but I'm not sure what you're asking in the second part. The ailerons/spoilers are not used to 'turn' the aircraft on the ground. Apart from the flight control check, the ailerons/spoilers are only used to keep the wings level during take-off with a strong cross-wind.
3) Direct law is same as Normal law's ground mode. Each SS deflexion has a programmed aileron/spoilers movement at each speed. But in direct law, this is true on ground AND flight. Right?
Direct Law is similar to Normal Law's Ground Mode, but it is not exactly the same. In Direct Law, the aileron/spoiler deflection is proportional to the sidestick deflection, regardless of speed and regardless of whether the aircraft is on the ground or in flight.
To complicate things, in Direct Law the maximum elevator deflection varies as a function of CG, to ensure adequate controllability. With an aft CG, the maximum elevator deflection with full sidestick will be less than that with a forward CG. Similarly, the maximum aileron/spoiler deflection varies according to the slat/flap configuration. When the aircraft is clean, the maximum aileron/spoiler deflection with full sidestick will be less than that when the slats/flaps are extended.