Yes, possible, could be hard work with 2 toddlers though.
I flew NZ-UK on my own with 7 mo dd, which was OK as she wasn't moving yet.
I flew with Singapore who are great if you're travelling with kids. If you want to have a break between the flights, Singapore airport has a transit hotel you can book in four-hour blocks where you can sleep, have a shower and eat, without having to go through customs/immigration and collect all your luggage etc. I think you can stay there up to 48 hours between flights. Obviously you are inside all the time as you are in transit section, but the airport is huge, has shops, playgrounds, swimming pool, free cinema etc. There is another Asian airport with same kind of transit horel but can't remember which.
Or you can bite the bullet and go straight through without a break between flights.
I'd advise flying with someone who has TV screens in backs of seats so your dcs can watch - they have loads of kids films/programmes on amongst the millions of channels available.
Good luck! I'm not going to attempt the flight again while dd is a toddler as she would rampage around the plane, but I know people who have managed it.
Fare sounds about right but you could get cheaper, is there a flight comparison website you could use?