[Need help for project. 12v Regulator]

Hey all, Nathan here.  I'm new to this board, and looking for some tips.
I'm new to electronics.

I am making a portable video streamer.  It's ghetto, and there are a slew of easier ways to meet my goals, but these are the parts I have available, and so I want to try and find a way to make it work.

I have an Anton Bauer battery that is typically 16vdc, but can fluctuate 12v-17v.  It's an 8 amp source.
I'm trying to power a 12v encoder, that may require up to 2.5 amps.

I have several small 12v solid voltage regulators from radio shack (I don't hace access to the P/N right now), at first they seemed perfect.  But they can only supply up to 1 amp.

I know so little that finding the right part is becoming more and more frustrating.  After this project I plan to spend a good amount of time getting up to speed, possibly taking some electronics classes.  I would love to finish this first though.

I considered 3 of the Radio Shack regulators I have in series.  From my online research it seems likely that I could reach my target of 12v, with enough current to supply 3 amps.  But I'm not confident enough to test it out on my only encoder.

I went to a store in town and got the closest thing I could identify as a possible solution. 
A nte970 Linear Integrated Circuit 3-Terminal Adjustable Positive Voltage Regulator.
What a name!

There are some inherent flaws with this part. 
Firstly, apparently my knowledge is far too lacking to know what to do with it.
Secondly, it's called a "3-terminal regulator", but it only has 2 terminals to my eyes.

I'd love some help.  I don't mind buying a regulator or some various other part.  I just want this to work.

Sorry for the long post for such a simple problem.  I'm prone to long-windedness.

Thanks for your time.

-Nathan