Helicopter VFR regulations that are different from airplanes
§91.119 - Minimum safe altitudes: General.
Helicopters are able to fly below the minimums of airplanes provided that "each person operating the helicopter complies with any routes or altitudes specifically prescribed for helicopters by the FAA."
This means as long as there aren't any specific restrictions set in place by the FAA, then a helicopter may descent to any altitude as long as the pilot in command deems it safe to himself and the surroundings.
The FAA has given the following statement:
"Helicopter operations may be conducted below the minimum altitudes set for fixed-wing aircraft."
The reason? The helicopter's unique operating characteristics. The most important of which is its ability to execute pinpoint emergency landings during power failure. Furthermore, the helicopter's increased use by law enforcement and helicopter air ambulance requires added flexibility in the application of many FAA provisions.
§91.126, 127, 129 - Operating on or in the vicinity of an airport in Class G/E/D airspace.
The general rule is that helicopters should avoid the flow of fixed wing traffic. The FAR/AIM says fixed wing traffic should make left traffic at airports, which means helicopters are left with making right traffic. These guidelines do however differentiate from airport to airport. An example is X51 (uncontrolled) where helicopters and fixed wing traffic are to make the same turns due to regular parachuting in one of the corners of the airport. In this case the helicopters must remain vigilant as to now blend in with the fixed wing traffic. In case of a controlled airport, the controller will usually make sure helicopters are routed around airplanes.
§91.151 - Fuel requirements for flight in VFR conditions.
Fuel requirements for helicopters are straight forward. All you'll need is 20 minutes of fuel left when you're back on the ground day and night.
§91.155 - Basic VFR weather minimums.
The weather minimums are largely the same for helicopters and airplanes except for golf airspace below 1200 ft. AGL. In this are, helicopters will only need to remain clear of the clouds and have at least half a mile visibility during the day, and 1 mile visibility during night time.
§91.157 - Special VFR weather minimums.
Helicopters are able to request special VFR (SVFR) during day and night even when the visibility is less than 1 mile. In contrast, an airplane would only be able to request SVFR with at least 1 mile visibility during the day, and the pilot would need an instrument rating during night time.