Currently about half of the cadet Pilots have been let go and the rest will be once their training is complete. This gives a small pool that can be called on should there be the need.
The limited flying currently being undertaken is mostly using the B787 or A350. The A330 and B772 ER are on their way out within a year. The other B777s are too big and the A380 is too big and too expensive for current demand.
Previously, an expat was someone employed for a defined period on a contract which might be renewed subject to need. Various allowances and perks were given over those enjoyed by pilots on local terms in order to attract talent and compensate for lack of job security.
Expats are increasingly rare in Singapore as the country has developed and doesn’t need to pay a premium for hardship living. Typically they are more likely to be found in the financial field. Foreigners are generally paid the same as locals now.