‘High speed stall’ is usually associated with transonic characteristics and thus is only loosely associated with ‘stalling’. Spinning is not a great concern, as indicated above.
The effect of high altitude turbulence on a VLJ should not be any greater than for other aircraft excepting any major aerodynamic differences. I suspect that VJLs might be more responsive than heavier aircraft, but likewise the control response should be quicker. There is little reason for any aircraft to stall in turbulence as all certifications require an aerodynamic control margin for such eventualities.
Re wake turbulence, then normal ATM procedures should take minimise the most severe encounters.
All ‘following traffic’ will have distance margin, and the preceding wake turbulence will be descending and disipating. Any following traffic 1000ft below might encounter some effects, but where this is detected a small track offset can be used. Similarly, crossing traffic should not suffer any marked effects.