Transit at Guangzhou (international to high speed train and vice versa)

I will fly from Singapore to GZ to take the high speed train to Guilin. I would like to find out
1) transit procedure at Baiyun airport via international flight
2) where to take the high speed train station from Baiyun airport
3) how much time should I cater for the transit from international flight to high speed train (and vice versa)
4) transit procedure to Baiyun airport via high speed train (when I return from Guilin via high speed train)

Thanks in advance.