Icing disrupts the aerodynamic qualities of wings and props, is there a similar danger with helicopter rotors? Are there de-icing systems to prevent this?
Yes, helicopter blades are no different from wings and propellers when it comes to ice, and there exist rotor de-ice and anti-ice systems for helicopters that require the ability to fly in known icing conditions, typically military types. Some examples include the Sikorsky S-92 and MH-60, and the Kamov Ka-50.
Rotor anti-icing systems are usually electric devices like heated mats, which are mechanically simpler that typical fixed-wing solutions like pneumatic boots and bleed-air-heated leading edges.
Not only the blades require anti-ice systems, however: elements like the engine intakes and air data sensors also need to be kept free of ice just like in fixed-wing aircraft.
Anti-ice systems for helicopter rotors are still not in any widespread usage. This would require a large current supply through some sort of slip ring or somehow directing bleed air to the spinning rotor blades. Leonardo Helicopters has just recently introduced the technology to their line of medium to heavy models. What you see on most helicopters is called a Leading Edge Abrasion Strip. They look somewhat like "anti-ice boots" used on fixed wing aircraft.