Even though the ethnic background of a majority of Singapore is Chinese-origin, English is standard language of instruction in schools and you’d rarely, if ever, come across anyone who doesn’t speak English. You don’t have to learn a new language.
Excellent base for travelling. Whether you are looking for full-service airlines or budget airlines, there’s a lot of choice and the sheer amount of competition keeps prices low. Alternatively, most of the neighbouring countries are also accessible by fairly good (by Asian standards, not considering East Asia) rail, bus, ferry/water links.
Fairly relaxed standards for issuing work visas. Taxation rates are low compared to developed country standards. This is one of the reasons why there’s a huge expat population in Singapore (again, a good thing or a bad thing depending on the way you see it) with almost a quarter of the population being foreigners. You also mentioned you work in IT while your wife works in real estate, which is great because these both sectors are booming in Singapore.
Working hours. Average on-contract working hours range from 8-10 hours. From what I have heard, that depends on how high up the ladder you are. If you are just starting off your career, some workplaces in Singapore expect you to work without overtime pay while others do pay for overtime. This is what I’ve heard from recent graduates, so your mileage may vary. I did a research internship for a couple of months and had flexitime, and could even telecommute whenever I wanted.
It’s close to Australia. Depending on what you desire, this may be a good thing (can meet family easily) or a bad thing (too close to where you already live).