A first time visit to Hong Kong

I and my wife intend to visit HK on 21July and leave on 23 July on our way from Sri Lanka to Australia. Our flight is to arrive in HK at 0830 on 21st and flight to Australia is at 1030 on the 23rd. Can you please suggest 2 simple itineraries for the afternoon on the 21st and one for the entire day on the 22nd which should include a visit to Giant Buddha Statue in Ngong Ping. As we do not have a lot of money to spend on big hotels and taxis will you kindly suggest a simple place to stay where we can use public transport from airport and for all the places you suggest us to see.
Appreciating your service greatly,
Somasiri from Sri Lanka