From Beijing Capital Airport to Tianjin the easiest way

Hi,

I am travelling from Europe, arriving to PEK at 1155AM. I've understood that its a Airport Express train for ~25RMB and then two different subway lines to get to Beijing South Railway Station. How long will the ride to BJ South take? What are the number of the subways (incl direction)?
From BJ South, I will go to Tianjin Station, with the high-speed intercity, at what time do you suggest I book this?

Best regards//Rikard