From Mongkok, you could take Hong Kong metro(https://www.travelchinaguide.com/cityguides/hongkong/transportation/subway.htm) to get to these places easily. To the peak&madame tussauds, you could take the metro and get off at Central. The Giant Buddha could be reached from Tung Chung station. The ferry terminal is located in walking-distance from Tsim Sha Tsui station.