It seems that your downwash speed in the hover in feet per min is roughly equivalent to your RoD in autorotation so, once you know this you can avoid VRS by keeping RoD at slow speed to less than half of that figure.
First part true - second part untrue and dangerous (since <900fpm will obviously not keep you safe)
Obviously bfcl is correct - zero airspeed is zero airspeed - makes no difference whether your ground speed is negative or positive at the time.
((except during the windsheer element perhaps at low level - where it counts and 'downwind' would be better ironically)).
VRS requires 2 elements:
Induced Flow (ie Powered flight)
and
An
opposing airflow (ie combination of low airspeed (eg less than 3kts) and a RoD (eg more than 3 kts)
Fully developed VRS is elegant and the 'buffeting and random attitude changes' generally stop.
Also buffeting and uncommanded pitch, roll and yaw is a pretty poor warning indicator since although they most often do occur, you
can just slip neatly into VRS without experiencing those first - if your really lucky.