カードの種類を選択する時、右側のOther Visa/MasterCardを選択すれば、購入に進めると思います。左側は、シンガポール発行のカードのみのようです。

オラウータンは動物園に入り、近くに行けば見たり写真を撮ったりすることはできます。朝食には参加しませんでしたので、近さの度合いはわかりません。 事前にネットで予約購入は可能です。英語のページですが。 ナイトサファリのチケットも日本語トラムのチケットも事前に同じページから購入可能です。動物園と合わせると割引があります。 私は歩いて回りましたが、トラムのコースとは別でした。トラムですと説明があるのでわかりやすいかと思います。ご参考までに。

当日でも購入できますが、他の方もコメントしている通り、事前購入をおススメします。シーズンにもよりますが、チケット購入だけでかなり並ぶ事もあります。

I wasnt aware it was considered wheelchair unfriendly? Grabbing the map and looking at it to remind myself. THe zoo is built with slopes wherever possible. Some areas are steep though - the Baboon area, and up and down to Reptopia are places where there are some steep sloping and the same for some access points to the Primate kingdom but is a lower steepness access point for those areas (though the less steep one for the baboons still has somewhat of a slope. With someone assisting with the chair Id say they would still be completely accessible on the steeper slope access routes although those points would be more of a challenge when self pushing. The trams either have some wheelchair slots, the ability to help you into a seat and transport the chair (though I wouldnt use the tram to get around myself even able bodied). In Fragile Forest you wouldnt be able to get up onto the feeding platform |(steps) but you would be able to go around the exhibit. Elephants of Asia has steps to seating but has a dedicated wheelchair seating area, so does the Shaw Foundation Amphitheatre. All the marked toilets include a disabled toilet Given those I have seen wheeling round or using the rentable mobility scooter Id say it appears fairly well adapted - though I dont have the full perspective a wheelchair user would have.

The ticket sale office is a room next to the entry gates, this is in the undercover area where the food court is. You can pre pay to save time depending when you go. If on hols, midweek is a good time, far less crowds. You can take the shuttle bus from Khatib Station, Bus is located pretty much at the last bit of undercover awning outside station. Enjoy

There is a digital map you can download on entry.

Rain doesnt get a refund on regular tickets. I would assume the same holds for SRVs. I have seen a number of youtubers visit during rain and they never mention getting refunds but I cannot cite personal experience as Im just a regular visitor to Singapore not a resident. Try it and report the result would be my other answer.

Around $35 US dollar. Including night safari. Very hot and humid make sure just wear light clothes especially walking for hours. Buy your ticket online coz maybe too crowded, to make sure and to avoid the long line. Enjoy and have a fun trip.

Taxis in Singapore are safe, reliable and reasonable in pricing. You may take a shuttle bus from Khatib MRT station directly to the zoo or book the Mandai express if you are going to the zoo on weekends and public holidays. However my suggestion is to take a taxi back after a whole day of walking and exploring. Tickets to both the Parks can be purchased in a combo set from the zoo website. You get a 20% discount if your purchase it online. Enjoy your trip!