The forummers and I are happy to help wherever we can and no need to worry about repeating anything.
1) Your son is well within the cut-off age. It is used to 11 and now 12/13 (this has been a moving target)
2) Send an email to CMPB, Mindef when you get your green card and tell them the following
- when you left and that your family have migrated to the US
- they will need a copy of your green card and the passport page showing date of entry to the US / date of green card
- ask all the questions that you need.
- provide your address and contact details as the replies are always in the mail except
3) exit permit is required when your son reaches 13 years of age. Since you provided the contact details they will notify you as reminder
4) the exit permit will allow your son to remain outside until the time for NS registration which is 16.5. Again reminder will be sent
5) No need to provide bond. Some clerk will sometimes might get it wrong but for migrants there is no bond.
6) In the meantime, do not do the following
- renew his passport
- apply for NRIC
- enroll for school in Singapore even if the parents have been posted by the company here etc
- in essence he cannot enjoy the privileges of this state
7) At 16,5, register online for NS, they will send you a form and they will now give your son deferment until the age of 21.
8) By this time, I suppose you guys will be US citizens. Your son is now a dual citizen and no issues as it not illegal.
9) He still cannot renounce his citizenship until he reaches age 21
10) At 21, Mindef will send reminder about 2 month before his 21 birthday and ask him to decide if he wants to keep his Singapore citizenship and if so he must turn up for NS. Or else apply to renounce. If he choses the latter, Mindef will provide contact details on who contact in ICA to renounce, Send email to that person and they will send the relevant forms which is quite tedious to fill. ICA will take 3 months to give the renounciation letter which must then be furnished to Mindef
11) During all these years, he can visit Singapore with no issues.
There is gap between the expired Singapore passport and getting the US passport after naturalisation. Do no renew the Singapore passport. Ask your relatives to fly to the US or a nearby country to meet. For family emergencies, Green card holders can apply to the US authorities for a travel paper which are temporary which are used for such purposes and for those who are stateless.
Enjoy your new life in a great new world. Very best to the family and you.