From Shenzhen to Wuhan

I will go from SZ to Wuhan by bullet train on 31 March about mid day , could you please answer my question below :

1. What station in SZ I have to depart?
2. Can I buy ticket directly on the day of departure(go show) or I have to book earlier?
3. If I book now from Jakarta, can I collect the ticket at the station on the day of departure?
4. How long it takes from Kowloon to train station in SZ? (I will stay in Kowloon before departure to
SZ)

Thank you,
Harnowo