birth registeration

Yes. Just sign a declaration form at ica. Both have to be there. But do take note that the moment you put his name, your child will be illegitimate child. Even you 2 legalised your marriage at a later part in future you have to set will for this child if not he or she won't get anything.

Yes my hubby and me got married in japan. Doesnt matter where your marriage should be legalised. If you're worried you can go ROM pay 60-80 I forgot how much and get a SG Marriage cert with the date of marriage as per the one you did overseas.

You should register your marriage in SG too

You can check with the embassy on details.

It depends if you are going ROM or ROMM

Yes .. u can

Yes, you may

Can

Can