It's hard to answer the first question on internet research. I did come across this from the
Civil Aviation Departments ArchiveIn 1962, a passenger terminal building was built. Turboprop aircraft were being replaced by jets such as the Boeing 707, DC8 and de Havilland comet. The first Boeing B747 arrived on 11 April 1970. In those days to use runway 13 pilots were required to have the runway in slight when the aircraft was near Cheung Chau Island.
In 1974, the visual approach was replaced by the Instrument Guidance System (IGS). With the aid of the IGS the runway could become visual to pilots when they were over the Kowloon Peninsula. This significantly increased the utilization of runway 13 under adverse weather conditions particularly during long periods of easterly prevailing winds.
Don't know the answer to the colour scheme questions though.