I force carb as I'm sure most do, but either will work fine. If you prime in the keg you'll just have blast it with enough pressure once filled & primed to seal it properly.
Some tips I've learned through trial and error...
When force carbing, the most foolproof way is to simply set your regulator to whatever your serving pressure will be (often around 10-12 psi depending on style of beer and fridge temperature) and let sit for a week or two. Rather than 30-40 psi for a couple of days then reducing it to serving pressure once carb.
This eliminates the possibility of "over-carbonating" your beer which I had issues with on my first batch.
But once you get the hang of things you can start tinkering with the process.
Another issue I had initially was that my beer line was to short.
Longer lines (6-10 ft) offer more resistance resulting in a slower pour with less foam. Length required again depends on the style of beer your dispensing as this will dictate the level of carbonation you'll be aiming for but anything in that ballpark will usually be fine
As far as what you'll need to buy...
Keg kit - Will include kegs, taps, connectors, lines, regulator, all the bits & pieces you'll need for the guts of your kegerator.
Fridge - If you're going with a bar fridge make you sure you have enough clearance height wise taking into account the freezer section.
CO2 bottle - Sometimes included in keg kit but if not will need to purchase separately otherwise.
And as far as setting it up, there's really nothing to it when you break it down...
Gas goes to keg - keg goes to tap - tap pours to glass
I was a little daunted myself when I received my keg kit but in hindsight, that's really all there is to it.
And honestly there's so much info on here that any questions you could possibly have, have already been asked and answered a hundred times over.
That probably sounds like of info but hopefully it'll answer some of your questions without creating too many new ones
