You've got some good advice hear so far. You need to break this down into segments, or it can become overwhelming to a newcomer into kegging.
You already have a way to store the cold kegs and your solving a way to serve them. Did your new tower come with faucets (taps if you will) and shanks? If not, you'll need those.
Working backwards, you will need beer line from the faucets to the kegs. I agree with the poster above that recommended replacing the existing beer line. There are calculators used to determine the length of beer line. I do not have one at my finger tips right now. I believe
@day_trippr has one he recommended quite a bit.
Now you'll need a way to connect the beer line to the kegs. Do you have kegs yet. There are a few different styles used by the homebrew crowd. I use ball lock, there's pin lock and sanke as well. Do a little research to see what would be best for you.
Now you'll need a way to get the gas into the kegs. You could use one cylinder with a single regulator and a "Y", or you could use a manifold. To get 2 different pressures you could do a 2 body regulator on the cylinder, do a secondary regulator(s), or have 2 cylinders each with a regulator. I would seriously consider a dual body regulator on the cylinder as mentioned above (also called a primary regulator). There is probably going to be a day you want 2 different pressures. With just a single body regulator and a manifold or "Y" you are stuck to one pressure. This will also give you the ability to have a spare cylinder (which you'll end up using for closed tranfers and other things in the future, trust me)
I highly recommend using the MFL fittings as much as possible. They make moving things around a breeze.
Lastly, I've had great luck at
Ritebrew.com. I'm not affiliated with them in any way, but they have great prices and they shipping has been very fast for me.
Take it one section at a time and it will be easier to plan everything out.