i think Not , because you Never die a 90 days in Person you Need to ask for a confirmation to have access to the system , they will give it to you , then online no problem.....here on phuket
For your extension you need the normal papers means a letter from the bank and depending where you live a copy of all pages of the bank book to show it was always in.....for the second question , here on phuket they will ask you at the next 90 days stamp, they ask to see that still 400 are in the bank.....but as you know ...not every time ....depending on the officers
I would do it here if all you company papers ready....or give it here to your accountant of lawyer ....it's easier the a new one abroad , for SIN you need to go trough an Internet ap.....so same result , be quick here