i realise you may have finished the thread, but just in case you check again, i grew up in different cities in oz,uk,us and spore and ended up going to 13 primary and secondary schools...
each move was entirely different and each culture suited one of us (me and 2 brothers) more than the others - almost as if we were suited to a city, and we all now live in separate countries. our personalities changed as we grew; with my brothers doing a flip around, with the shy one becoming extremely outgoing, and the more attention seeking one becoming quite restrained.
all three of us are keenly aware that many of the experiences we have had, we can only share between us - and that's kept us close emotionally, if not physically - skype is great. though none of us have life-long friendships with others and envy other people for that. though we've had close friends and varying degree of popularity in all the places we lived, the friendships haven't really gone the distance - and that's partly, sad to say because of a sense of inevitability of moving each time. that said, you won't be moving anywhere near so often, so its entirely probable that wouldn't develop in your dc. the friendships my brothers and i miss are all from the teenage years - so your dcs will have plenty of settled time for this.
also, if you go to spore,whilst there; have you thought whether to educate your children in english or us system. the return journey will be easier iyswim. though the local system was pretty good, there was still an emphasis on rote learning 20 years ago - has prob changed though
i found developing an extra curricular skills that can be transferred to any culture/school useful also. i ended up joining the drama club/choir at each school and made friends quicker because of this. it also gave me a personal context for my education, if that makes any sense.
s'pore can be a great place, as you know, especially for young children. it would be a wonderful and exciting eyeopener for your dc to experience living in a 'westernised' rather than 'western' country. ah the food alone!!!
though it would take them a while to get used to Singlish - this probably sounds silly - any chance of getting some s'pore shows recorded? it makes a huge diff being able to understand what's being said to you. (i couldn't learn anything at school for the first month in each new country - as completely baffled by accents!) Singlish is particularly different from UK-US because of
the inventiveness and resulting word play of having English/Hokkien/Malay and Tamil all mashed together. Also the relative lack of hearing it in the media.
Hope any of these thoughts help - the more preparation you can do with your children about Singapore, the better. Libraries should have children's fact books on Singapore - but may be worth buying some if you intend on going through with the move. It may even get you excited about going. Keep it light and fun if you can - if you have more of an attitude of adventure it could be more reassuring. I remember my mum going through a book on the US and we'd planned to watch the trash compactor in the sink after seeing it in a diagram of the typical US home
i wish you so much luck and strength and easy transitions for you and your fam, esp ds1.