Going to Hong Kong on May 20-23 with my friends, with planned itenirary as follows.

Yes, your plan is doable. D1: if you have enough time, the Sky 100 near Kowloon is also a worthy destination. D2: I do like your plan. Aside the Wax Museum, the peak tower should not be missed.

As for your plan, the MTR may be the best tranport for you. For the peak, it is suggested to take the tram to reach.

For the transportation and directions, here is my general advice:
D1: walk from your hotel to Causeway Bay MTR Station to take Island Line to Admiralty, where transfer to Tsuen Wan line to Tsui Sha Tsim. For your destinations, you can walk around to have a visit.

D2: To Ocean Park, you can take Island Line to Admiralty. Near its MTR Station, you can easily find bus no. 629, which can take you to the park directly. AFter that, you can take the bus back to Central and walk to Garden Road to take tram to the peak to visit the attractions on.

D3: Also take Island Line to Admiralty, where transfer to Tsuen Wan Line to Lai King Station. At this station, transfer to Tung Chung Line to Tung Chung Station, from which you can walk to the cable car station to catch the cable car to Ngong Ping 360 and Giant Buddha. After that, you can go to Tung Chung MTR Station to take Tung Chung Line to Sunnybay, where transfer to Disney Resort Line to the attraction directly.

D4: You can walk around to go shopping. Oh, Time's Square shall never be missed.