All that aside you need to decide on what type of serving system is your end goal. There are 4 basic "end goal" type systems with several stopping points where it can still serve yet not be completely finished.
You can serve from any of them with a basic picnic tap that is attached via a short piece of tubing. Looks like this.
Using a deep freeze to make a "Kreezer" (Keg-orator + Freezer, is how the world is derived).
Staring out looks like this.
Starting all you need is a deep freeze, a temperature controller and a basic picnic tap. Starting out all you need to do is open the lid and serve via the picnic tap.
They look like this finished.
This one is "collared" as there's a wooden collar added for the taps to attach to.
This one is "towered" as there's a tap tower attached to the lid for the taps.
If this is your goal using Ball lock kegs (which are more narrow) will allow you to fit more kegs, but in some cases will require some sort of collar since they are taller. Pin locks are wider so there you may not get as many kegs in but you most likely won't need a collar because they are not as tall.
Using a standard Refrigerator.
Looks like this finished
This one has the taps mounted out to front door.
Starting out all you need is the refrigerator and a basic "picnic" tap open the door to serve. Ball locks would be ideal here because height is generally not an issue as width and depth are.
A Stand-up Freezer is a combination of the above. You'll need a temperature control like the freezer, yet you can mount taps to the door like the refrigerator.
Finally is a mini-fridge type. These are available commercially produced that look like this.
Or they can be hand build out of "dorm"/mini fridges and look like this.
Starting out just as before you'll need the fridge and a picnic tap. Ball locks are almost the only choice for this as the largest mini fridges aren't much wider then 18" inside.
Based on what you like from this post, crossed with what you'd like to pay for kegs from the post above the decision is yours to make.
