you need pay S$15 for deposit, and they can not confirm with you if we can play wow in singapore, but from what i read in various forum, most likely we can play in singapore using gamecard. you can call them and use internet-banking to transfer the booking deposit. here is the contact, hope useful to you.

#05-15 Funan The IT Mall
Tel: 68373248
Hp: 93879522
Email: deli@gamescore.com.sg

monthly fee. for blizzard only accept the visa or mastercard from the 4 country, i believe it is not ture.
Frist case Except USA, the other 3 are all in British Union like singapore, the credit systems are all the same i believe. 2nd, I heard that someone has sign up the new account use Japan Visa card already.
I also heard that from 30th onward the gamecard will be sold widely because there are a lot of students who play wow and do not have CC. For myself, I want to buy the WOW CE even I can not play right now, it does not matter even I have to wait a few months to play it.
Do not worry, I believe blizzard maybe do some restriction on wow players but Singapore is an exception since Singapore is in SE Asia( this place will not have a WOW official server in the future), Singapore is more close to all Westen countrys(eg, Aus, Canada, US and NZ) in both social and economic relationship than other Aisa countrys.

Btw my id is randomsin6 and randomsin7(Current one) in UW, i just play some arranged team and RT 2v2, seldom play solo.