If you all want my personal opinion, Do Not come to Singapore for Greener Pastures! Come here if you have a job option to make some good money for a couple of years then get the hell out of Dodge. Singapore is not the place to immigrate to. It is a flash in the pan that to me has a max of 40 more years tops. While they are on the top of the heap in S.E. Asia at the moment, it is not sustainable. Not for their want of trying, but they cannot slow down the advance of their neighbours. Eventually, their neighbours will overtake them and with natural resources, will bury Singapore.
And, if you have sons who you allow to become PR's they will have to do NS. Which is not a bad thing. But that's my personal opinion as well. Being a Yank I'd rather my son did it here in aircon comfort rather than in the US and possible in some ill-conceived war that we didn't ask for.
Course you could always keep them on Student passes or keep them in
International Schools and on student visas. If you don't have a job beforehand think seriously about it. You might be better off thinking about Australia which also has a large SA Community from what I understand. I know they import gem squash down there anyway!
It would be better if you or your husband do not have a position before arriving here, to land with LPR. Especially if you are planning a grand exodus without any guarantees (not the best way I can assure you) or employment prospects. It would be better to only have one come over and get set up first.