I'll be trying to take the high speed rail from Beijing South to Tanggu and grabbing a cab to TEDA.

I plan on printing the hotel address out in Chinese to show to the cab driver. Other than that, how would I get train tickets? I can speak some Chinese but my reading is not very good. I hear you guys talking about Ctrip, but I see that Ctrip only delivers tickets, and not in Beijing. Are there other sites where I should buy my high speed rail tickets at? Or would I be ok showing up at the train station to buy tickets? I imagine it's pretty hectic there at commute hours right?

I've only done the HSR once in Suzhou and our supplier took care of everything. Not sure I could do it all on my own that efficiently unless I knew where the ticket windows were for foreigners, etc.

You don't need to pre book tickets for that route, it is pretty much an extension of the subway with trains running every 10-15 mins.

There are ticket machines with an English option and you will need to scan your passport.

This is like the subway. Just show up and get ticket for the next available train.
If you really feel uncomfortable then contact www.china-diy-travel.com

I thought the tanggu schedule wasn't quite that frequent because most trains terminate in Tianjin.

Yeah. I just need to catch the last train before 6 or so. But if people are saying that I shouldn't worry about tickets being sold out (non holiday wkd), then I guess I should be ok.

I wouldn't sweat it. Your fallback option is to take a train to Tianjin and cab it the rest of the way.

Any special machines I need to look for, or are they all over the place? Sorry for all the questions. I just remember at Suzhou we ran around in circles with my supplier until they could find the right counter for us, but if Beijing South is filled with easy to use kiosks, then I just want to make sure they're all usable for foreigners (because it seems many sites say that the kiosks require Chinese ID??)

The machines with passport readers are pretty hard to miss but buying a ticket from a human being is also an option (this honestly doesn't take very long).