The cruising speed varies from about 130 km/hr to 275 km/hr depending on the model. An Aeropatiale SA.360 (275 km/hr), Silvercraft SH-4 (130 km/hr).
A fast aeroplane will be faster than any helicopter, but a fast helicopter can be faster than a slow aeroplane.
quite fast, there is more drag from the fuselage going side ways and it would be less stable
Quite a subjective question. This depends on the type of rescue helicopter, in the UK the follow are used: Westland Sea King HAR3 or HAR 5: 129 mph (112 knots, 208 km/h) (max cruise at sea level)...
232mph