Surie Park Island is a really nice place to live. I'm a resident and can tell you its a very relaxing place to live, kind of a resort feeling to it. All residents will tell you as soon as we arrive on the island we feel very relaxed. There are regular busses and ferry services. For taxies, from Central or Sheung Wan its a very quick 15 min trip home. And when you catch a taxi, there are almost always taxies waiting at the main taxi stand to Park Island/Ma Wan. All the locals also have "local taxi numbers" that you can use to call discount taxis.
In terms of access for vehicles, many women live on the Park Island who are pregnant. When its due for baby (or any other emergency) the ambulance can come in very quickly. So that is absolutely no problem.
The comment about humidity makes no sense to me. I have found Central HK to be and feel much more himid than Park Island. On Park island the air is cleaner (due to less cars and less highrises) and these is often a nice breeze. Some people don't even use aircons and just open windows for the ocean breeze.
Whilst there are plenty of parents with young kids on the island, there are also many singles/couples. For you, the best thing I would say is the relatively affordable pricing of the apartments, very high quality of everything there, the peacefulness at night, and all the great facilities like the pools, gyms, tennis courts etc. You will have no problem at all meeting people there.
There is a local facebook for Park Island residents called The MaWan Network. If you join that you will see many friendly residents who can help you out. We use it to sell second hand stuff, complain, discuss, gossip etc but also to help each other out Feel free to PM me if any questions about living there, but in summary, for many reasons (and I have lived in many places in HK) it really is a very good living place.