Hi,
well, I guess it will be best for you to try the cadetship programmes as its the most economical way a singaporean takes.
as for SIA cadets, yes they do have a job, but they are still at the risk of getting chopped due to many factors, thus in the aviation world there are no things like 'comfrimed' placing. There are surely many cadets whom get dropped out of SFC and its stringent criterias meant that only the best will get through the 3-4yrs of training... So by gettting the FO contract then one may say that they have a pilot job with SQ, if not uncertaintly still remains, but at the lower side then self-sponsored cadets in SFC or any other flight schools.
Great way to fly