Bullet train fair to Hong Kong from Guangzhou and HOW to book ticket in advance from Malaysia.

Hi im Jefri, need to know best advice frm you. Landed at GZ airport frm KUL on 25 Dec 2013. need to take bullet train to HK next day.
1. How much will it cost me n my family for return ticket with bullet train for 4 adults and 01 children to HK and back to GZ? if possible CN currency to Ringgit conversion.
2. How to book the bullet train tickets in advance from Malaysia?

Thanks