The set up you show has a Sanke coupler for American commercial style kegs. You would need ball or pin lock (depending on your kegs) gas and beer couplers. The tower shown has one faucet, so to run 4 kegs you would also need either 3 more towers and faucet combos or a tower that had 4 faucets. You also will likely need more 3/16" beer line to balance the system than is shown for each tap (I use about 10 feet...there are other threads about this), a gas manifold to split the gas to each of the kegs, some gas line to run from manifold to kegs....
I opted for the collar, for ease of build, but agree that the tower looks nice. I just finished my build and am still learning about my system....see my blog for info/pics.....I didn't detail the building, but talk about the problems and show the freezer.
Oh, and my chest freezer had a nice plug in the back of the lid (and no coils in the lid, either) where I could run electric into, but your gas could go through that too, just drill through the insulation. There are a number of nice plug in style controllers available at HBS if you don't want to worry about wiring and mounting something like a Love controller.
good luck. It is a fun and satisfying build when complete.